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Understanding LLM Performance Degradation in Multi-Instance Processing: The Roles of Instance Count and Context Length
Jingxuan Chen, Mohammad Taher Pilehvar, Jose Camacho-Collados
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Summary
This paper evaluates the performance of sixteen Large Language Models (LLMs) in Multi-Instance Processing (MIP) tasks, where models must process and aggregate multiple input instances. The study finds that LLM performance consistently degrades as the number of instances increases, with a significant performance collapse observed beyond 1,000 instances. The research demonstrates that while context length is a factor, the number of instances is a stronger driver of performance degradation, and identifies specific failure modes including parsing errors, aggregation mistakes, and individual instance-level errors.
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LLM → exhibitsdegradationin → Multi-Instance Processing (MIP)
confidence 100% · The results show that all LLMs follow a pattern of slight performance degradation for small numbers of instances
Instance Count → strongereffectthan → Context Length
confidence 90% · our analysis shows that while context length is associated with this degradation, the number of instances has a stronger effect on the final results.
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Find all LLMs evaluated in the study · confidence 90% · unvalidated
MATCH (m:LLM) RETURN m.name
Identify factors affecting performance degradation · confidence 85% · unvalidated
MATCH (f:Factor)-[:AFFECTS]->(p:PerformanceDegradation) RETURN f.name, p.description
Abstract
Abstract:Users often rely on Large Language Models (LLMs) for processing multiple documents or performing analysis over a number of instances. For example, analysing the overall sentiment of a number of movie reviews requires an LLM to process the sentiment of each review individually in order to provide a final aggregated answer. While LLM performance on such individual tasks is generally high, there has been little research on how LLMs perform when dealing with multi-instance inputs. In this paper, we perform a comprehensive evaluation of the multi-instance processing (MIP) ability of LLMs for tasks in which they excel individually. The results show that all LLMs follow a pattern of slight performance degradation for small numbers of instances (approximately 20-100), followed by a performance collapse on larger instance counts. Crucially, our analysis shows that while context length is associated with this degradation, the number of instances has a stronger effect on the final results. This finding suggests that when optimising LLM performance for MIP, attention should be paid to both context length and, in particular, instance count.
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- Source: https://arxiv.org/abs/2603.22608v1
- Canonical: https://arxiv.org/abs/2603.22608v1
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Understanding LLM Performance Degradation in Multi-Instance Processing: The Roles of Instance Count and Context Length Jingxuan ChenMohammad Taher PilehvarJose Camacho-Collados School of Computer Science and Informatics, Cardiff University ChenJ192,PilehvarMT,CamachoColladosJ@cardiff.ac.uk Abstract Users often rely on Large Language Models (LLMs) for processing multiple documents or performing analysis over a number of instances. For example, analysing the overall sentiment of a number of movie reviews requires an LLM to process the sentiment of each review indi- vidually in order to provide a final aggregated answer. While LLM performance on such in- dividual tasks is generally high, there has been little research on how LLMs perform when dealing with multi-instance inputs. In this pa- per, we perform a comprehensive evaluation of the multi-instance processing (MIP) ability of LLMs for tasks in which they excel individually. The results show that all LLMs follow a pat- tern of slight performance degradation for small numbers of instances (≈20–100), followed by a performance collapse on larger instance counts. Crucially, our analysis shows that while con- text length is associated with this degradation, the number of instances has a stronger effect on the final results. This finding suggests that when optimising LLM performance for MIP, attention should be paid to both context length and, in particular, instance count. 1 1 Introduction LLMs have demonstrated remarkable capabilities across a wide range of natural language process- ing tasks and beyond (Wang et al., 2024). How- ever, these capabilities have been predominantly evaluated in settings where a single instance is pro- vided to the model at a time, which we refer to as single-instance processing (SIP). In contrast, many real-world applications, such as data analytics, doc- ument analysis, and large-scale information pro- cessing, require multi-instance processing (MIP), where the model generates individual predictions for multiple instances and subsequently aggregates them into a single, cohesive final prediction. The 1 Data and code are available athttps://github.com/ jingxuanchen916/multi-instance-processing. Review 1: Charming, funny, and surprisingly smart... Single-Instance Processing: Is this review positive or negative? 樂 易LLM Positive ✅ Review 2: Beautifully shot and emotionally honest... 易 LLM Positive ✅ Review 3: Predictable story with wasted potential... 易 LLM Negative ✅ Review 1: Charming, funny, and surprisingly smart... Multi-Instance Processing: How many reviews are positive? 類 Review 2: Beautifully shot and emotionally honest... 易 LLM 3 Positive ❌ Review 3: Predictable story with wasted potential... Figure 1: A toy example of SIP and MIP settings for sentiment analysis, where an LLM succeeds under SIP but fails under MIP given the same instances. ability of LLMs to process multiple instances has been studied in recent literature in different con- texts such as data analytics (Chen et al., 2025; Rah- man et al., 2025; Sun et al., 2025) and long-context settings (Bertsch et al., 2025; Liu et al., 2025; Qiu et al., 2024; Shaham et al., 2023; Wolfson et al., 2026), which we unify and formalise under the MIP umbrella in this work. Compared to SIP, MIP poses additional chal- lenges due to its long-context nature and the need to perform repeated reasoning and aggregation over multiple instances, making it substantially more demanding for current LLMs (Bertsch et al., 2025). Ensuring reliable performance in such set- tings therefore requires a careful understanding of model failure modes, in order to inform the devel- opment of effective mitigation strategies for MIP. As a motivating example, consider a non-expert user who inputs multiple movie reviews and wishes to determine how many of them are positive. Fig- ure 1 illustrates a toy comparison between SIP and MIP: while an LLM can correctly classify the sen- timent of each review in isolation, it may fail when required to process and aggregate all instances 1 arXiv:2603.22608v1 [cs.AI] 23 Mar 2026 within a single prompt. Given that the model is ca- pable of accurately handling individual instances, it is crucial to understand the nature of the errors that arise when multiple instances must be processed jointly. Although alternative solutions, such as agentic designs that process instances separately or require users to manually batch instances or write code, are possible, these approaches are often im- practical for non-expert users in real-world settings. Existing work has extensively examined the challenges posed by long-context inputs, showing that model performance often degrades as context length increases, even when inputs remain within the model’s nominal context window (An et al., 2025; Moon and Lim, 2025). However, in most long-context benchmarks, increasing input length is accompanied by a simultaneous increase in task complexity (Hsieh et al., 2024). This coupling makes it difficult to disentangle whether observed performance degradation arises from longer inputs per se or from increased semantic and reasoning de- mands. In parallel, multi-instance or batch process- ing settings have been explored in prior work, but primarily from an efficiency or cost-reduction per- spective, and typically with relatively small batch sizes (Cheng et al., 2023; Lin et al., 2024a). As a re- sult, the effect of scaling the number of instances it- self on model performance remains underexplored. Given these gaps, we propose two research ques- tions (RQs) to better understand LLM behaviour in MIP settings: 1.How does LLM performance change in MIP settings, and what failure behaviours emerge as the number of instances increases? 2. What are the primary drivers of performance degradation in MIP? Do instance count and context length have similar effects? To answer these RQs, we evaluate sixteen LLMs across a diverse set of eight tasks, including calcu- lation, token-level and sentence-level classification, for which they are known to perform well when only individual instances are provided. We analyse a broad range of open-weight and closed-source LLMs, and systematically examine the limits and factors that influence their performance in MIP. Our results show that model performance typically de- grades gradually for small instance counts before collapsing at larger scales, and that this degrada- tion is more strongly associated with the number of instances than with context length alone, even when the latter is substantially increased. 2 Related Work The practical demand for MIP is typically driven by the use of LLM-based agents for complex data ana- lytics, such as data wrangling, exploratory analysis, and multi-file reasoning (Guo et al., 2024; Hong et al., 2025; Nam et al., 2025). In these workflows, data processing is a foundational step and often requires transforming heterogeneous inputs into in- termediate representations or executable code (Lin et al., 2024b; Shankar et al., 2024). While current approaches typically adopt modular pipelines to im- prove reliability through task decomposition (Nam et al., 2025; Shankar et al., 2024), these systems are ultimately bounded by the LLM’s ability to handle high-density information. Understanding the lim- its of such analytical workflows therefore requires examining LLM performance along two critical di- mensions: the capacity to maintain coherence over long contexts and the ability to process multiple inputs efficiently through batch processing. Long Context. Recent benchmarks have ex- amined LLM performance degradation in long- context settings, spanning retrieval-based evalua- tions (Hsieh et al., 2024; Levy et al., 2025; Yang et al., 2025b), long-context reasoning over dis- persed evidence (Kuratov et al., 2024; Vodrahalli et al., 2024; Zhang et al., 2024), and broader application-oriented suites (Yen et al., 2025). Com- plementary work also studies specialised regimes, including long procedural generation (Ye et al., 2025), scalable mathematical reasoning (Zhou et al., 2025), narrative understanding (Hamilton et al., 2025), and long-term conversational mem- ory (Wu et al., 2025). Closest to our work, Bertsch et al. (2025) evaluates long-context information ag- gregation via many in-context instances, but varies task difficulty primarily through context length rather than isolating the effect of increasing the number of instances. Batch Processing. Recent works study whether LLMs can answer multiple questions within a sin- gle prompt, typically motivated by reducing infer- ence cost and balancing capacity limits (Cheng et al., 2023; Ji et al., 2025; Lin et al., 2024a). These studies consistently observe that only a small num- ber of instances can be processed reliably before accuracy degrades. However, they do not investi- gate scaling behaviour beyond this regime, which arises in many practical settings where non-expert users may directly pass all instances to an LLM. 2 Moreover, their evaluations primarily focus on in- dependent question answering (Wang et al., 2025) or classification tasks (Gozzi and Di Maio, 2024), rather than controlled settings in which task seman- tics are fixed and the instance count itself is the primary source of difficulty. 3 Multi-Instance Processing We study MIP, where an LLM is required to rea- son over multiple input instances within a single prompt. In contrast to retrieval-augmented genera- tion (RAG), which typically uses only a subset of retrieved inputs to produce the final answer, MIP re- quires processing all provided instances. As shown in Figure 1, LLMs must iterate over all instances individually in MIP to produce intermediate results, which are then aggregated into a final answer. An instance is defined as a single data entryx (e.g., a movie review, a user post, a sentence, or a number). LetXdenote the set of all available instances. The modelMis provided with a subset X ′ ⊆X, where the number of instancesn =|X ′ | may vary across inputs. SIP is treated as a special case of MIP where n = 1. 3.1 Formulation Given a task instruction promptτand an input instance setX ′ = x 1 ,...,x n ⊆ X, the model M , parameterised by θ, generates an output o∼ p θ (·| τ,X ′ ), wherep θ denotes the model’s conditional output distribution. A valid model output typically contains an ag- gregated predictiony agg together with a natural language explanationr. Lety agg⋆ denote the corre- sponding ground-truth aggregated label. An output is considered correct when the aggregated predic- tion matches the ground truth, i.e.,y agg = y agg⋆ . Otherwise, it is considered a wrong output and be- longs to the setW. The model may also produce an invalid output, in which case it fails to generate a well-formed prediction. Such outputs belong to the setI. We define both wrong answers (i.e., valid but incorrect outputs) and invalid outputs as failures: E fail =W ∪I. We writeo∈E fail to denote that a model output is a failure. 3.2 Filtering for Controlled Difficulty An important aspect of our methodology is ensur- ing that the evaluated tasks are simple enough for LLMs to solve when individual instances are pro- vided (i.e., in SIP settings). Therefore, to control instance-level task difficulty when evaluating MIP, we construct inputs based on SIP outcomes. LetX SIP ⊆ Xdenote the subset of instances for which all comparison models can produce the correct prediction under the SIP setting. MIP in- puts are then formed by uniformly sampling sub- setsX ′ ⊆X SIP using fixed random seeds. To fur- ther ensure reliable evaluation, we retain only mod- els whose average SIP task success rate exceeds 95% and whose per-task SIP success rate exceeds 90%. We also keep only tasks for which agreement among all retained models exceeds 85%, measured as the proportion of instances that all comparison models answer correctly prior to filtering. Our filtering procedure ensures that failures ob- served in the MIP setting are not attributable to intrinsic instance difficulty or ambiguity, but in- stead reflect the model’s ability to reason over and aggregate multiple instances, which is the primary focus of this work. 3.3 Evaluation Metrics We define an experiment as a specific evalua- tion configuration represented as a tuplee = (M,τ,X ′ ), which produces a model outputo e . We define accuracy as a binary metric. Lety agg e de- note the aggregated prediction extracted from the model output o e . Then: Acc(e) = ( 1, if y agg e = y agg⋆ e , 0, otherwise. LetDdenote the set of all evaluated experiments. The success rate (SR) is defined as the average accuracy across experiments: SR = 1 |D| X e∈D Acc(e). The invalid rate (IR) measures the fraction of ex- periments in which the model produces an invalid output: IR = |e∈D | o e ∈I| |D| . 4 Experimental Setting In this section, we describe our general experimen- tal setting. 3 NameTask Arithmetic Solve arithmetic problems & Sum of answers Category Classify news category & Aggregate class counts Language Identify language & Aggregate class counts NER Count “person” entities & Aggregate total counts Parity Detect odd or even number & Aggregate counts Sentiment Detect sentiment polarity & Aggregate counts Word Count target word “women” & Aggregate total counts WSD Identify “apple” word sense & Aggregate counts Table 1: Overview of the selected tasks and their ag- gregation logic in the MIP setting. More details can be found in Appendix A. 4.1 Individual Tasks We consider eight heterogeneous tasks 2 for our analysis, as summarised in Table 1. Each task is chosen such that it can be solved individually in the SIP setting by standard LLMs. When multi- ple instances are provided in the MIP setting, the model is tasked with additionally aggregating out- puts across all instances (e.g., counting how many movie reviews are classified as positive in senti- ment analysis). Detailed task descriptions and ex- amples are provided in Appendix A. 4.2 Models and Prompting We use OpenRouter 3 to evaluate sixteen LLMs, in- cluding nine open-weight models (DeepSeek R1, DeepSeek V3, gpt-oss-120b, gpt-oss-20b, Llama 3.3, Llama 4 Maverick, MiniMax M2.5, Qwen3- Instruct and Qwen3-Thinking) and seven closed- source models (Claude Sonnet 4.6, Gemini 2.5 Flash, Gemini 3.1 Pro 4 , GPT-5, GPT-5 Nano, Grok 4 and Grok 4 Fast). 5 For prompting, we use a temperature of 0 and a maximum output length of 20K tokens for con- sistency across models. To allow limited tolerance 2 We removed three additional tasks whose SIP perfor- mance fell below our requirements. 3 https://openrouter.ai 4 We used the preview version, which was the only version available at the time of experimentation (March 2026). 5 As with the task filtering, we removed two open-weight LLMs, Llama 4 Scout and Mistral NeMo, whose SIP perfor- mance did not meet our criteria. to formatting errors, we permit up to three retries when a model produces an invalid output belong- ing toI. The full set of prompting templates is provided in Appendix B. 4.3 Single-Instance Filtering As described in Section 3.2, we ensure that each in- stance can be successfully solved in the SIP setting. To this end, we conduct SIP experiments on 2,500 instances for each task. 6 We report each LLM’s SIP performance for each task in Appendix C.1. Moreover, Table 7 in Appendix C.2 reports the per- centage of instances retained (i.e., agreement) for each task (from 89% to nearly 100%), and the cor- responding maximum and minimum SIP success rates across models, all exceeding 93%. Finally, as described in Section 3.2, this filtering retains only instances for which all comparison models agreed on the correct answer, thereby excluding potentially ambiguous instances and annotation errors. 4.4 MIP Sampling After single-instance filtering, for each task τwe construct MIP inputs by sampling in- stances fromX SIP using five different ran- dom seeds (s ∈ 1, 2, 3, 4, 5).We eval- uate ten MIP sample sizesn ∈ N = 2, 5, 10, 20, 50, 100, 200, 500, 1000, 2000 . For each(τ,n,s), we prompt each modelMwith the corresponding instance set, retaining only instances for which all models are correct in the SIP setting. 5 RQ1: Performance and Failure Behaviours Our main goal is to evaluate LLM performance and failure behaviours in MIP settings, particularly as the number of instances increases. 5.1 Performance Analysis Gradual success rate degradation followed by collapse as the number of instances increases. Figure 2 reports success rates aggregated across tasks for each model. We observe a consistent per- formance degradation as the number of instances increases. In particular, all models show notice- able drops above 200 instances and near-collapse beyond 1,000 instances, with success rates falling 6 The original dataset of Category contains fewer than 2,500 instances, and each instance is substantially longer. We therefore use 250 instances instead of 2,500 for this task. Cor- respondingly, the maximum MIP sample size for Category is also ten times smaller than for the other tasks. 4 below 20% at 2,000 instances. Figure 3 shows suc- cess rates aggregated across models for each task and reveals a similar downward trend. With the exception of Arithmetic, all tasks achieve success rates above 60% when fewer than 50 instances. Per- formance then deteriorates steadily as the instance count grows. Complete results by model and task are reported in Appendix D.1. LLM comparison. Table 2 reports the success rate and invalid rate for all models. Overall, closed- source LLMs do not consistently exhibit superior performance. While frontier proprietary models (GPT-5, Gemini 3.1 Pro and Grok 4) achieve the highest success rates, this advantage comes at sub- stantially higher cost. 7 Beyond them, Qwen3- Thinking, gpt-oss-120b, DeepSeek R1, Grok 4 Fast and GPT-5 Nano achieve the highest success rates (above 65%). Notably, only Llama 4 Maverick and Grok 4 Fast produce no invalid outputs, indicating greater robustness. While all models achieve suc- cess rates above 35% on average, Figure 2 indicates that most successful cases occur when fewer than 500 instances are processed. Robustness to instance order. To examine whether instance order affects LLM performance, we conduct an additional robustness experiment. For all experiments whose instance sets were orig- inally sampled with random seeds = 1, we ran- domly shuffle the instance order twice (usings = 6 ands = 7) and rerun the evaluation. Figure 4 re- ports the resulting success rates as the number of instances increases. The degradation patterns re- main highly consistent across different orderings of the same instance sets, suggesting that instance order has little effect on overall performance. 5.2 Failure Behaviours Beyond our default setting, which requires only an aggregated answer, we introduce an additional vari- ant for more fine-grained analysis. In this variant, models are required to produce instance-level pre- dictionsy i n i=1 before providing the aggregated answer. Even with such instance-level predictions, which provide explicit intermediate reasoning, the relative performance of models remains similar to the aggregated-only setting. As described in Section 3.1, we consider two broad categories of failures: wrong answers and 7 Given the high cost of frontier models and practical bud- get constraints, we restrict subsequent experiments to only lightweight closed-source and open-weight models. Model Size /SuccessInvalid Cost(%)(%) DeepSeek R1A37B67.5±2.62.9±0.6 DeepSeek V3A37B39.0±3.62.9±0.6 gpt-oss-120b117B68.3±2.83.6±1.1 gpt-oss-20b21B60.8±2.54.9±0.6 Llama 3.370B39.0±3.82.9±0.6 Llama 4 Maverick17B43.1±1.10.0±0.0 MiniMax M2.5A10B62.3±1.816.1±2.7 Qwen3-InstructA22B37.9±3.61.3±0.0 Qwen3-ThinkingA22B69.4±2.43.9±1.6 Claude Sonnet 4.6$ 4.6860.3±2.70.3±0.6 Gemini 2.5 Flash$ 0.4037.7±3.94.2±3.2 Gemini 3.1 Pro$ 6.2880.3±1.42.6±0.9 GPT-5$ 2.6481.8±2.61.8±0.7 GPT-5 Nano$ 0.1366.5±3.87.5±0.6 Grok 4$ 5.5470.6±1.71.3±0.0 Grok 4 Fast$ 0.2667.0±2.80.0±0.0 Table 2: Model success rate and invalid rate (mean±std), averaged across all tasks and instance counts. Standard deviation is computed over five random seeds. The top nine models are open-weight LLMs (DeepSeek R1, DeepSeek V3, MiniMax M2.5, Qwen3-Instruct, and Qwen3-Thinking are all mixture-of-experts LLMs, with total parameter counts of 671B, 671B, 230B, 235B, and 235B, respectively), where we report model size. The bottom seven are closed-source LLMs with undisclosed sizes, for which we report the average cost per task across five runs. invalid outputs. Wrong answers include errors at the individual-instance level, the aggregation level, or both. Invalid outputs include (1) parsing er- rors, where the model output cannot be reliably parsed into the expected structured format, and (2) overlong input errors, where the input exceeds the model’s allowable context length. To analyse fail- ure behaviours in greater detail, we use the instance- level variant in the following experiments. Different failure types emerge as the number of instances increases.Figure 5 presents a stacked bar plot showing the contribution of each failure type as the instance count increases. Blue bars correspond to wrong answers, while orange bars correspond to invalid outputs. Wrong answers can occur even with as few as two instances. When the instance count exceeds 200, parsing errors in- crease substantially and reach nearly 30% at 2,000 instances. Overlong input errors emerge mainly be- yond 200 instances, primarily due to the Language task, as non-English inputs typically require more prompt tokens (Petrov et al., 2023). 5 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate DeepSeek R1 DeepSeek V3 gpt-oss-120b gpt-oss-20b Llama 3.3 Llama 4 Maverick MiniMax M2.5 Qwen3-Instruct Qwen3-Thinking Claude Sonnet 4.6 Gemini 2.5 Flash Gemini 3.1 Pro GPT-5 GPT-5 Nano Grok 4 Grok 4 Fast Figure 2: Model success rates (averaged across all tasks) as a function of the number of instances. Error bars indicate standard deviation across five random seeds. LLMs from the same company share the same colour family, while markers denote categories:•(open-weight,≥37B active parameters),■(open-weight,≤22B active parameters),▲ (frontier closed-source), and♦ (lightweight closed-source). 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Arithmetic Category Language NER Parity Sentiment Word WSD Figure 3: Task success rates (averaged across all LLMs) as a function of the number of instances. Error bars indicate standard deviation across five random seeds. Mistakes in individual instances and aggrega- tion. To further characterise wrong answers, we categorise them into four error types: key mistakes (keys do not span from 1 ton), individual mistakes (at least one instance-level prediction is incorrect), aggregation mistakes (all instance-level predictions are correct but the aggregated answer is incorrect), and combined mistakes (both instance-level and aggregation errors occur). As shown in Figure 5, when the instance count exceeds 100, combined mistakes increase markedly, accounting for approx- imately 25% to 45% of failures. Moreover, when aggregation mistakes and combined mistakes are considered together, aggregation remains challeng- ing for LLMs regardless of instance-level correct- ness or instance count. Complete results by model and task are reported in Appendix D.2. 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Original Order Shuffled Order (Seed = 6) Shuffled Order (Seed = 7) Figure 4: Success rates as a function of the number of instances for the original instance order and two shuffled variants constructed from the same instance sets. Model differences in making mistakes.Table 3 compares models in terms of how individual- instance mistakes are distributed across experi- ments. Some models tend to concentrate many individual mistakes within a small number of failed experiments, while others exhibit more frequent but sparser errors. Focusing on individual mistakes, we observe that each failed experiment of Grok 4 Fast typically contains many incorrect instance- level predictions. In contrast, Gemini 2.5 Flash more often produces failed experiments with only a small number of individual mistakes, and Mini- Max M2.5 shows low values in both metrics. Self-awareness of limitations. Ideally, an LLM should recognise its own capability boundaries. A desirable behaviour is for the model to explicitly acknowledge in its reasoningrwhen it cannot han- 6 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 3.5% 6.9% 6.5% 4.6% 4.2% 18.1% 11.2% 8.8% 24.6% 23.8% 15.4% 23.3% 4.2% 32.5% 14.0% 18.8% 9.0% 15.5% 40.5% 9.3% 13.6% 5.2% 15.5% 18.3% 44.0% 7.1% 11.2% 18.8% 27.1% 29.3% 22.1% Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error Figure 5: Breakdown of failure types. Key mistakes, aggregation mistakes, individual mistakes, and combined mistakes (Agg.+Indi.) are categorised as wrong answers (blue), while parsing errors and overlong input errors are categorised as invalid outputs (orange). Model Wrong Exp. Wrong Indv. Per Exp. DeepSeek R121.0±3.749.5±9.9 DeepSeek V329.6±2.734.8±13.1 gpt-oss-120b16.2±2.937.5±17.4 gpt-oss-20b15.8±2.411.8±5.0 Llama 3.335.6±2.253.8±26.7 Llama 4 Maverick33.6±4.238.4±4.6 MiniMax M2.58.2±1.55.8±5.5 Qwen3-Instruct29.4±2.120.8±3.1 Qwen3-Thinking16.0±2.915.4±4.0 Gemini 2.5 Flash13.4±1.35.5±3.2 GPT-5 Nano11.2±3.110.3±15.3 Grok 4 Fast22.4±1.7117.3±8.0 Table 3: Percentage of experiments with at least one in- correct instance-level prediction (Wrong Exp.) and the average number of incorrect instance-level predictions per failed experiment (mean±std). Standard deviation is computed over five random seeds. dle a large number of instances (e.g., by suggest- ing batch-wise processing or explicitly stating that the instance count exceeds its capacity). Such be- haviour can be reflected by the model producing predictions for only the first few instances and omit- ting the remaining ones, which corresponds to a key mistake (missing key). After inspecting the model outputs, we found that only 171 out of 4,620 ex- periments exhibit this omission, almost exclusively at instance counts of 500 or more, as expected. However, a manual analysis shows that only 27 out of these 171 experiments explicitly suggest batch- wise processing, and most models do not warn users about such limitations. GPT-5 Nano demon- strates this behaviour most frequently, explicitly in- dicating difficulty in 19 out of 28 cases. In contrast, DeepSeek V3, gpt-oss-120b, and gpt-oss-20b do so in fewer than 20% of its omission cases, while no such behaviour is observed for the remaining mod- els. Notably, although Qwen3-Instruct and Gemini 2.5 Flash do not acknowledge limitations, they also produce almost no cases of this omission. 5.3 Discussion Overall, our findings answer RQ1 by showing that as the instance count increases, all LLMs experi- ence degraded performance, characterised by lower success rates and more frequent failures. In par- ticular, when the instance count reaches 1,000 or higher, no LLM achieves a success rate above 40%. Among the evaluated LLMs, GPT-5, Gemini 3.1 Pro, Grok 4, gpt-oss-120b and Qwen3-Thinking exhibit the strongest overall performance. Focus- ing on the lightweight and open-weight models, although Gemini 2.5 Flash achieves relatively low success rates, its failures typically involve a rel- atively small number of incorrect instances. At the same time, invalid outputs become increasingly common as the instance count grows. Notably, GPT-5 Nano is the only model that consistently identifies when a task exceeds its capacity. 6 RQ2: Context Length vs Number of Instances In the previous section, we analysed LLM be- haviour in MIP settings as the number of instances increases. The results revealed consistent perfor- mance degradation across all models, albeit at dif- 7 ferent rates and to different extents. A natural ques- tion is whether this degradation is driven by in- creased context length, as has been observed in prior work across a range of tasks and settings (see Section 2). In this section, we analyse the effects of context length and instance count jointly, and examine their respective contributions. 6.1 Context Length Augmentation To study the impact of context length, we design a setting in which the length of each individual instance is artificially increased without altering its original content. 8 For each sampled instance x, we construct a perturbed instancex ′ = x + ε, whereεdenotes injected noise. Following Hsieh et al. (2024), we defineεas the string “- IRRELE- VANT CONTEXT START - ” followed by seven repetitions of the sentence “The grass is green. The sky is blue. The sun is yellow. Here we go. There and back again.”, plus “ - IRRELEVANT CON- TEXT END -”. This choice is motivated by prior work showing that even irrelevant context can de- grade model performance (Shi et al., 2023; Yang et al., 2025a). After noise injection, the average length of each instance (measured in the number of prompt tokens) more than doubles, increasing from approximately 136 tokens in the default setting to 326 tokens in the artificially augmented setting. Results.Figure 6 compares average performance across all tasks and models between the default and artificially augmented settings, as the number of instances increases. When the number of instances is held constant, the success rates of the two set- tings remain broadly similar, despite the average context length being more than twice as large in the augmented setting. This indicates that artifi- cially increasing the length of individual instances does not substantially impact performance, sug- gesting that context length alone is unlikely to fully explain the performance degradation observed in MIP settings. Complete results by model and task are reported in Appendix D.2.2. Robustness to noise position. To further exam- ine whether the position of injected noise affects model performance, we vary where the noise is inserted for the same instance set sampled with 8 We exclude Parity from this experiment because each instance contains only a single number. For consistency with context length constraints, we also cap the maximum sample size atn = 1000in this setting (n = 100for Category), as discussed below. 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Default Augmented 0 50K 100K 150K 200K Context Length Figure 6: Success rate (lines) and total prompt token length (bars) in the artificial length setting as the num- ber of instances increases. Error bars indicate standard deviation across five random seeds. 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Tail Head Middle Random Figure 7: Success rates as a function of the number of in- stances for different injected-noise positions constructed from the same instance sets. s = 1. In addition to the tail setting used above, we also insert the noise at the head, in the middle, and at random positions within each instance. Fig- ure 7 shows that the performance remains broadly similar across these variants, indicating that the po- sition of injected noise does not lead to substantial performance differences. 6.2 Correlation Analysis Motivated by the above findings, we conduct a correlation analysis to further examine the relation- ships of instance count and context length to overall model performance. Recall that in our default set- ting, instance samples are constructed using five random seeds. While this random sampling intro- duces some variation in individual instance lengths, the average prompt length tends to be similar across samples, especially when the number of instances is high. To obtain a wider range of context lengths for correlation analysis, we augment the default 8 Number of Instances Success rate and Context length CorrelationP-Value 20.0430.498 50.0440.491 100.0440.490 20-0.0420.510 50-0.0330.602 100-0.0140.823 2000.0560.420 5000.1170.102 1000-0.0530.475 Table 4: Correlation between success rate and prompt token length when the number of instances is fixed. samples with two additional variants drawn from X SIP : a long set, consisting of the longest instances in each dataset, and a short set, consisting of the shortest instances. This design enables a clearer comparison across different context lengths by in- troducing greater variation in total input length. Correlation with instance count and total con- text length. As an initial analysis, we compute the Spearman correlation between success rate and each factor independently: the number of instances and the total context length. Both factors exhibit strong negative correlations, indicating that per- formance decreases as either quantity increases. However, the number of instances shows a notably stronger relationship, with Spearman correlations of−0.61, compared to that of−0.37for the con- text length. In both cases, the correspondingp- values are below0.001, indicating that the correla- tions are highly unlikely to arise by chance. Correlation conditioned on the number of in- stances. The two factors are inherently related, as total context length grows with the number of instances. To better understand their effects, we ad- ditionally compute correlations while holding the number of instances fixed and examining variation only in context length. As shown in Table 4, the resulting correlations between context length and success rate are substantially weaker, with values ranging between−0.15and0.15, andp-values con- sistently above0.1. These results indicate that con- text length alone has limited explanatory power in this setting and suggest that the performance degra- dation observed in Section 6.1 is more strongly associated with the number of instances than total input length. 6.3 Discussion Based on the above results, we find that the num- ber of instances plays a stronger role than context length in determining model success rates. When the number of instances is held fixed, the effect of context length appears to be comparatively limited according to our correlation analysis. LLMs have been shown to struggle when required to perform many repeated operations (Son et al., 2024; Fu et al., 2024), which is precisely what MIP entails as the instance count increases. This behaviour contrasts with RAG settings, where models primar- ily need to identify relevant contexts rather than process all inputs exhaustively. In MIP settings, LLMs must process each instance individually and aggregate the resulting outputs. While prior work has shown that LLMs can handle increasingly long contexts (Liu et al., 2025), our findings suggest that improving reliability in MIP settings may also re- quire training strategies that explicitly target multi- instance reasoning and aggregation. 7 Conclusion In this paper, we presented a comprehensive eval- uation of LLMs in MIP settings, that is, tasks that require aggregation of information from multiple instances to produce a final answer. The results show that LLMs are generally able to solve tasks involving a small number of instances, but begin to make mistakes as the number of instances increases. While the errors are initially small, this has impor- tant implications for user trust, since models are able to consistently solve the task when only a sin- gle instance is given. Moreover, as the number of instances further increases, models’ performance starts collapsing, in most cases without any warn- ing to the user that this may happen. Crucially, our experiments on context length highlight the importance of reasoning at the instance-count level, rather than focusing solely on context length as is commonly done. This has implications for how context should be processed in batches, for example when developing data sci- ence agents. Instead of relying only on context length for batching decisions in MIP settings, we should also consider the number of instances as a relevant factor. More generally, our results suggest that models may benefit from training strategies that better support multi-instance reasoning and aggregation, especially in settings where accuracy and user trustworthiness are paramount. 9 Limitations This work focuses on diagnosing failure modes of LLMs in multi-instance processing (MIP) settings, rather than proposing or validating concrete solu- tions. While our controlled evaluation reveals per- formance degradation as the number of instances increases, we do not evaluate mitigation strategies such as task decomposition, external tool use, ver- ification, or agentic designs. As a result, this pa- per should be interpreted primarily as an empirical characterisation of model behaviour rather than as a prescription for improving MIP reliability. Our experiments emphasise exact aggregation tasks (e.g., counting, summation, exact class fre- quencies). Although these tasks are common in analytics-style applications, they may overempha- sise brittleness in settings where approximate or semantic aggregation would suffice. The extent to which our findings generalise to softer aggregation objectives (e.g., majority voting, summarisation, or trend identification) therefore remains an open question. In addition, our experiments rely on a fixed prompt template across tasks, which may not fully capture the variability of prompt formulations encountered in real-world applications. Despite our efforts to examine the roles of in- stance count and context length, these two factors are not entirely independent in practice. While correlation and controlled noise-injection analyses suggest that instance count has a stronger relation- ship with degradation, more fine-grained causal analyses (e.g., controlled computational complex- ity or attention-level diagnostics) are left for future work. Moreover, we did not stress-test LLMs with extremely large context inputs, which might have given different results and perhaps a stronger con- text length effect. Finally, our study does not include model- internal interpretability analyses such as attention patterns or hidden-state dynamics, nor does it evalu- ate training-time interventions. In addition, our ex- periments are English-centric and limited to a set of selected LLMs, due to time and budget constraints. Future work could explore cross-lingual MIP be- haviour and architectural or training modifications explicitly designed for multi-instance reasoning. Ethical Considerations This work presents an empirical evaluation of LLMs in multi-instance processing settings and does not involve the collection of new data, in- teraction with human subjects, or the deployment of models in real-world decision-making systems. All datasets used in our experiments are publicly available and open-source, and were accessed and processed in accordance with their original licences and intended research use. Also, we do not claim that any particular model or provider is inherently unsafe or unsuitable. Rather, our results reflect general limitations of current LLMs under spe- cific experimental conditions. We hope that this work contributes to more responsible deployment of LLM-based systems by encouraging practition- ers to consider instance-level reliability, aggrega- tion strategies, and potential failure modes when designing real-world applications. Acknowledgments Jose Camacho-Collados was supported by a UKRI Future Leaders Fellowship. References Chenxin An, Jun Zhang, Ming Zhong, Lei Li, Shansan Gong, Yao Luo, Jingjing Xu, and Lingpeng Kong. 2025. Why does the effective context length of llms fall short? In The Thirteenth International Confer- ence on Learning Representations. 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SIP Ground Truth Output: 1. 251,862 2. -9,259,431 3. -1,140.09 MIP Question:Solve all the provided arithmetic questions and calculate the sum of all answers. MIP Ground Truth Output: -9,008,709.09 A.2 Category The task is about news category classification, where a news article can belong to “tech” or “busi- ness” or “entertainment” or “politics” or “sport”. The dataset is BBC News (Greene and Cunning- ham, 2006), where we use its training split. The average word count for this task is 371.4. Example Input: 1. german business confidence slides german business confidence fell in february knock- ing hopes of a speedy recovery in europe s largest economy... 2.bbc poll indicates economic gloom citizens in a majority of nations surveyed in a bbc world service poll believe the world economy is worsening... 3.lifestyle governs mobile choice faster better or funkier hardware alone is not going to help phone firms sell more handsets research sug- gests... SIP Ground Truth Output: 1. business 2. business 3. tech MIP Question:Count how many of the provided news articles belong to the “tech” category. MIP Ground Truth Output: 1 A.3 Language The task is about language identification, where a paragraph can belong to “English” or “Chinese” or “Persian” or “Spanish”. The dataset is WiLI- 2018 (Thoma, 2018). The average word count for this task is 55.8. Example Input: 1.Nordahl Road is a station served by North County Transit District’s SPRINTER light rail line... 2. En Navidad de 1974, poco después de que interpretó la canción en francés película Papil- lon (Toi qui Regarde la Mer)... 3. A talk by Takis Fotopoulos about the Interna- tionalization of the Capitalist Market Econ- omy and the project of Inclusive Democracy... SIP Ground Truth Output: 1. English 2. Spanish 3. English MIP Question:Count how many paragraphs are in English. MIP Ground Truth Output: 2 A.4 NER The task is about named entity recognition, which uses data from WikiANN (Rahimi et al., 2019). The average word count for this task is 16.0. 13 Example Input: 1. we love everything about the fence . 2.i want to hook up with that girlpaigein the brown leather jacket . 3.in addition , there is a reduction of 22,101 mmbtu which is the difference between the scada values ( best available ) thatanita showed on the february 29th storage sheet and the " official " february 29th values that gary wilsonreceived from mips . SIP Ground Truth Output: 1. 0 2. 1 3. 2 MIP Question: Count occurrences of the entity ’PERSON’ in all sentences. MIP Ground Truth Output: 3 A.5 Parity The task is about parity classification (i.e., identify if a number is “odd” or “even”), where we use synthetic data generated by ourselves. The average word count for this task is 1 since only a single number is provided. Example Input: 1. 18010 2. 10160 3. 89449 SIP Ground Truth Output: 1. even 2. even 3. odd MIP Question:Count how many of the provided numbers are odd. MIP Ground Truth Output: 1 A.6 Sentiment The task is about sentiment analysis, where a movie review can belong to “positive” or “nega- tive”. The dataset is Sentiment Treebank (Socher et al., 2013), where we only use the “most” posi- tive and negative reviews to avoid ambiguity. The average word count for this task is 18.7. Example Input: 1.High Crimes is a cinematic misdemeanor , a routine crime thriller remarkable only for its lack of logic and misuse of two fine actors , Morgan Freeman and Ashley Judd . 2. One of the worst movies of the year . 3. A mix of gritty realism , crisp storytelling and radiant compassion that effortlessly draws you in . SIP Ground Truth Output: 1. negative 2. negative 3. positive MIP Question:Count how many of the provided movie reviews are positive. MIP Ground Truth Output: 1 A.7 Word The task is about tweets word occurrence (i.e., count a target word’s occurrences in given tweets). The dataset is TweetEval (Barbieri et al., 2020), where we use its stance detection subset. The aver- age word count for this task is 17.3. Example Input: 1.IF FEMINISTS WERE HONEST “I want a worldwide matriarchal dictatorship with all men enslaved towomen” #GamerGate #SemST 2. What the fuck dowomeneven do? I mean seriously they’re just useless other than sex. #womensrights #Feminist #SemST 3. DEAR FEMINISTS Start asking for account- ability from man-haters instead of shielding them for convenient concealment. #SemST SIP Ground Truth Output: 1. 1 2. 2 3. 0 MIP Question: Count occurrences of the word “women” in all tweets. 14 MIP Ground Truth Output: 3 A.8 WSD The task is about word sense disambiguation, where a target word “apple” is required to be dis- tinguished as meaning either “company” or “fruit” based on its context. The dataset is CoarseWSD- 20 (Loureiro et al., 2021), where we use its “apple” subset. The average word count for this task is 31.4. Example Input: 1. both seasons are available for download from apple ’s itunes store . 2. in klayman i , the plaintiffs sued the same government defendants and in addition , face- book , yahoo! , google , microsoft , youtube , aol , paltalk , skype , sprint , at&t , apple again alleging the bulk metadata collection violates the first , fourth and fifth amendment and constitutes divulgence of communication records in violation of section 2702 of stored communications act . 3.description alongside dried pears the filling also contains raisin , walnut and other dried fruit such as apple or figs . SIP Ground Truth Output: 1. company 2. company 3. fruit MIP Question: Count how many paragraphs contain the word "apple" referring to the company (Apple Inc.), not the fruit. MIP Ground Truth Output: 2 A.9 Excluded Tasks Beyond the tasks mentioned above, we have three additional tasks that have been filtered out due to unsatisfactory SIP performance: • Bigram Shift detection: from SentEval (Con- neau and Kiela, 2018), which checks whether a bigram in a sentence has been shifted, with binary outcomes (i.e., shifted or not). •Subject Number identification: from SentE- val (Conneau and Kiela, 2018), which checks whether the subject of a sentence is “plural” or “singular”. •Voice classification: from Universal Depen- dencies (Silveira et al., 2014), which checks whether a sentence is in the “active” or “pas- sive” voice. Since no ground-truth labels are available, we use rule-based approaches to annotate the dataset. B Prompt Template Here we present the prompt templates we use in our experiments. We use the example inputs in Appendix A for illustration. B.1 Default Setting B.1.1 Arithmetic Task: Solve all the provided arithmetic questions and calculate the sum of all answers. ,→ ,→ Instructions: - Calculate the answer for each arithmetic operation,→ - Sum all individual answers - Provide exact values without unnecessary trailing zeros (e.g., "5" not "5.0") ,→ ,→ - Prefix negatives with'-' (e.g., "-42"),→ - For decimal results, keep only necessary decimal places (e.g., "3.14" not "3.140") ,→ ,→ - If you only receive one question, the sum is just its answer,→ Response format: Return a JSON object with: - "reasoning": briefly explain your calculation process,→ - "answer": sum of all answers as a string,→ Example: "reasoning": "your approach here", "answer": "42",→ === Here are the arithmetic questions ===,→ Question 1: What is the difference between -2 and 251860?,→ Question 2: -9259432 + 1 Question 3: What is 1141.09 less than 1? ... === End of arithmetic questions === 15 B.1.2 Category Task: Count how many of the provided news articles belong to the'tech' category. ,→ ,→ Background: - Each news article belongs to one of 5 categories:,→ * business * entertainment * politics * sport * tech - You need to classify each article based on its content and context,→ Instructions: - Read each news article carefully - Identify which category each article belongs to based on the content,→ - Count how many articles belong to the 'tech' category,→ - Do not count articles from other categories (business, entertainment, politics, sport) ,→ ,→ - If you only receive one article, return 1 if it's tech, else return 0,→ Response format: Return a JSON object with: - "reasoning": briefly explain your approach to classifying news categories and how you counted ,→ ,→ - "answer": integer count of tech news articles,→ Example: "reasoning": "your approach here", "answer": 42,→ === Here are the news articles === Article 1: german business confidence slides german business confidence fell in february knocking hopes of a speedy recovery in europe s largest economy... ,→ ,→ ,→ ,→ Article 2: bbc poll indicates economic gloom citizens in a majority of nations surveyed in a bbc world service poll believe the world economy is worsening... ,→ ,→ ,→ ,→ Article 3: lifestyle governs mobile choice faster better or funkier hardware alone is not going to help phone firms sell more handsets research suggests... ,→ ,→ ,→ ,→ ... === End of news articles === B.1.3 Language Task: Count how many of the provided paragraphs are written in English.,→ Background: The paragraphs are written in one of four languages:,→ - English (label 0) - Chinese (label 1) - Persian (label 2) - Spanish (label 3) Instructions: - Read each paragraph carefully - Identify the language of each paragraph,→ - Count how many paragraphs are written in English,→ - Do not count paragraphs in other languages,→ - If you only receive one paragraph, return 1 if it's English, else return 0 ,→ ,→ Response format: Return a JSON object with: - "reasoning": briefly explain your approach to identifying English paragraphs ,→ ,→ - "answer": integer count of English paragraphs,→ Example: "reasoning": "your approach here", "answer": 5,→ === Here are the paragraphs === Paragraph 1: Nordahl Road is a station served by North County Transit District's SPRINTER light rail line... ,→ ,→ ,→ Paragraph 2: En Navidad de 1974, poco después de que interpretó la canción en francés película Papillon (Toi qui Regarde la Mer)... ,→ ,→ ,→ 16 Paragraph 3: A talk by Takis Fotopoulos about the Internationalization of the Capitalist Market Economy and the project of Inclusive Democracy... ,→ ,→ ,→ ,→ ... === End of paragraphs === B.1.4 NER Task: Count how many times the entity "PERSON" appears across all provided sentences. ,→ ,→ Background: - An entity may consist of multiple words that form a contiguous fragment in the text ,→ ,→ - You need to first identify entities in the sentence (named entity recognition), then count them ,→ ,→ - Two entities may appear consecutively without punctuation or words between them ,→ ,→ - No entity overlaps occur (each word belongs to at most one entity),→ - Some words do not belong to any entity Entity Definition: - PERSON: names of people, real or fictional, but not nominals,→ Instructions: - Identify all PERSON entities across all sentences,→ - Count the total number of PERSON entity mentions (not unique entities, but total occurrences) ,→ ,→ - Each distinct mention counts as one occurrence, even if it refers to the same person ,→ ,→ Response format: Return a JSON object with: - "reasoning": briefly explain how you identified the entities and counted them ,→ ,→ - "answer": integer count of PERSON entities,→ Example: "reasoning": "your approach here", "answer": 5,→ === Here are the sentences === Sentence 1: we love everything about the fence .,→ Sentence 2: i want to hook up with that girl paige in the brown leather jacket . ,→ ,→ Sentence 3: in addition , there is a reduction of 22,101 mmbtu which is the difference between the scada values ( best available ) that anita showed on the february 29th storage sheet and the " official " february 29th values that gary wilson received from mips . ,→ ,→ ,→ ,→ ,→ ,→ ,→ ... === End of sentences === B.1.5 Parity Task: Count how many of the provided numbers are odd.,→ Background: - An odd number is an integer that is not evenly divisible by 2,→ - Odd numbers end in 1, 3, 5, 7, or 9 - An even number is an integer that is evenly divisible by 2,→ - Even numbers end in 0, 2, 4, 6, or 8 Instructions: - Check each number to determine if it is odd or even,→ - Count how many numbers are odd - Do not count even numbers - If you only receive one number, return 1 if it's odd, else return 0,→ Response format: Return a JSON object with: - "reasoning": briefly explain your approach to identifying odd numbers,→ - "answer": integer count of odd numbers Example: "reasoning": "your approach here", "answer": 3,→ === Here are the numbers === Number 1: 18010 Number 2: 10160 Number 3: 89449 ... 17 === End of numbers === B.1.6 Sentiment Task: Count how many of the provided movie reviews are positive.,→ Instructions: - Each review has a sentiment: positive or negative,→ - Count only the reviews with positive sentiment,→ - Return the total count of positive reviews,→ - If you only receive one review, return 1 if it's positive, else return 0,→ Response format: Return a JSON object with: - "reasoning": briefly explain how you solved this task,→ - "answer": integer count of positive reviews,→ Example: "reasoning": "your approach here", "answer": 42,→ === Here are the movie reviews === Review 1: High Crimes is a cinematic misdemeanor , a routine crime thriller remarkable only for its lack of logic and misuse of two fine actors , Morgan Freeman and Ashley Judd . ,→ ,→ ,→ ,→ ,→ Review 2: One of the worst movies of the year .,→ Review 3: A mix of gritty realism , crisp storytelling and radiant compassion that effortlessly draws you in . ,→ ,→ ,→ ... === End of movie reviews === B.1.7 Word Task: Count how many times the word "women" appears in the provided tweets. ,→ ,→ Instructions: - Search is case-insensitive (e.g., "women", "Women", "WOMEN" all count),→ - Count occurrences that include the substring "women" (e.g., "women", "womens", "women's", "womenfolk") ,→ ,→ - Do not count forms that lack the substring "women" (e.g., "woman", "womankind") ,→ ,→ - Count all occurrences across all tweets, not just unique tweets,→ - If you only receive one tweet, just return the occurrence for that tweet,→ Response format: Return a JSON object with: - "reasoning": briefly explain how you counted the matches,→ - "answer": integer total count Example: "reasoning": "your approach here", "answer": 42,→ === Here are the tweets === Tweet 1: IF FEMINISTS WERE HONEST "I want a worldwide matriarchal dictatorship with all men enslaved to women" \#GamerGate \#SemST ,→ ,→ ,→ Tweet 2: What the fuck do women even do? I mean seriously they're just useless other than sex. \#womensrights \#Feminist \#SemST ,→ ,→ ,→ Tweet 3: DEAR FEMINISTS Start asking for accountability from man-haters instead of shielding them for convenient concealment. \#SemST ,→ ,→ ,→ ... === End of tweets === B.1.8 WSD Task: Count how many paragraphs contain the word "apple" referring to the company (Apple Inc.), not the fruit. ,→ ,→ Background: - Each paragraph contains exactly one occurrence of the word "apple" (case-insensitive, as a complete word, not as part of another word) ,→ ,→ ,→ - This "apple" can mean either: * The company: Apple Inc., the technology company,→ * The fruit: the edible fruit that grows on apple trees,→ 18 - You need to determine the meaning of "apple" in each paragraph based on context ,→ ,→ Instructions: - Read each paragraph carefully - Identify whether "apple" refers to the company or the fruit based on contextual clues ,→ ,→ - Count how many paragraphs where "apple" means the company (Apple Inc.) ,→ ,→ - Do not count paragraphs where "apple" means the fruit,→ - If you only receive one paragraph, return 1 if it means the company, else return 0 ,→ ,→ Response format: Return a JSON object with: - "reasoning": briefly explain your approach to disambiguating the word sense and how you counted ,→ ,→ - "answer": integer count of paragraphs where "apple" means the company,→ Example: "reasoning": "your approach here", "answer": 42,→ === Here are the paragraphs === Paragraph 1: both seasons are available for download from apple's itunes store . ,→ ,→ Paragraph 2: in klayman i , the plaintiffs sued the same government defendants and in addition , facebook , yahoo! , google , microsoft , youtube , aol , paltalk , skype , sprint , at\&t , apple again alleging the bulk metadata collection violates the first , fourth and fifth amendment and constitutes divulgence of communication records in violation of section 2702 of stored communications act . ,→ ,→ ,→ ,→ ,→ ,→ ,→ ,→ ,→ ,→ ,→ ,→ Paragraph 3: description alongside dried pears the filling also contains raisin , walnut and other dried fruit such as apple or figs . ,→ ,→ ,→ ... === End of paragraphs === B.2 Instance-Level Setting B.2.1 Arithmetic Task: Solve each of the provided arithmetic questions and calculate the sum of all answers. ,→ ,→ Instructions: - Calculate the answer for each arithmetic question,→ - Use 1-based indexing for question numbers ("1", "2", "3", . . . ),→ - Provide exact values without unnecessary trailing zeros (e.g., "5" not "5.0") ,→ ,→ - Prefix negatives with'-' (e.g., "-42"),→ - For decimal results, keep only necessary decimal places (e.g., "3.14" not "3.140") ,→ ,→ - Sum all individual answers Response format: Return a JSON object with: - One key per question: "1", "2", "3", . . . , mapping to the answer as a string ,→ ,→ - "sum": sum of all answers as a string - "reasoning": brief explanation of your approach,→ Example for 3 questions: "1": "8", "2": "-30", "3": "5.6", "sum": "-16.4", "reasoning": "your approach here" ,→ ,→ === Here are the arithmetic questions ===,→ Question 1: What is the difference between -2 and 251860?,→ Question 2: -9259432 + 1 Question 3: What is 1141.09 less than 1? ... === End of arithmetic questions === B.2.2 Category Task: For each news article, classify it into one of 5 categories, then provide total counts for each category. ,→ ,→ ,→ 19 Background: - Each news article belongs to one of 5 categories:,→ * business (label 0) * entertainment (label 1) * politics (label 2) * sport (label 3) * tech (label 4) - You need to classify each article based on its content and context,→ Instructions: - Read each news article carefully and classify it into the most appropriate category ,→ ,→ - For each article, assign: * 0 if it's business news * 1 if it's entertainment news * 2 if it's politics news * 3 if it's sport news * 4 if it's tech news - Count the total number of articles for each category,→ - Provide classification for each article along with summary counts,→ Response format: Return a JSON object with: - One key per article: "1", "2", "3", . . . , mapping to the category label (0-4) ,→ ,→ - "business": integer count of articles classified as business,→ - "entertainment": integer count of articles classified as entertainment,→ - "politics": integer count of articles classified as politics,→ - "sport": integer count of articles classified as sport,→ - "tech": integer count of articles classified as tech,→ - "reasoning": brief explanation of your approach to news classification,→ Example for 3 articles: "1": 4, "2": 0, "3": 3, "business": 1, "entertainment": 0, "politics": 0, "sport": 1, "tech": 1, "reasoning": "your approach here" ,→ ,→ ,→ === Here are the news articles === Article 1: german business confidence slides german business confidence fell in february knocking hopes of a speedy recovery in europe s largest economy... ,→ ,→ ,→ ,→ Article 2: bbc poll indicates economic gloom citizens in a majority of nations surveyed in a bbc world service poll believe the world economy is worsening... ,→ ,→ ,→ ,→ Article 3: lifestyle governs mobile choice faster better or funkier hardware alone is not going to help phone firms sell more handsets research suggests... ,→ ,→ ,→ ,→ ... === End of news articles === B.2.3 Language Task: For each paragraph, identify which language it is written in, then provide summary counts for all categories. ,→ ,→ ,→ Background: The paragraphs are written in one of four languages:,→ - English (label 0) - Chinese (label 1) - Persian (label 2) - Spanish (label 3) Instructions: - Read each paragraph carefully and identify its language,→ - Classify each paragraph using the labels:,→ * 0 = English * 1 = Chinese * 2 = Persian * 3 = Spanish - Provide the classification for each individual paragraph,→ - Also provide summary counts for all four language categories,→ Response format: Return a JSON object with: - One key per paragraph: "1", "2", "3", . . . , mapping to the classification (0, 1, 2, or 3) ,→ ,→ - "english": integer count of paragraphs classified as English,→ 20 - "chinese": integer count of paragraphs classified as Chinese,→ - "persian": integer count of paragraphs classified as Persian,→ - "spanish": integer count of paragraphs classified as Spanish,→ - "reasoning": brief explanation of your approach,→ Example for 5 paragraphs: "1": 0, "2": 1, "3": 2, "4": 3, "5": 0, "english": 2, "chinese": 1, "persian": 1, "spanish": 1, "reasoning": "your approach here" ,→ ,→ ,→ === Here are the paragraphs === Paragraph 1: Nordahl Road is a station served by North County Transit District's SPRINTER light rail line... ,→ ,→ ,→ Paragraph 2: En Navidad de 1974, poco después de que interpretó la canción en francés película Papillon (Toi qui Regarde la Mer)... ,→ ,→ ,→ Paragraph 3: A talk by Takis Fotopoulos about the Internationalization of the Capitalist Market Economy and the project of Inclusive Democracy... ,→ ,→ ,→ ,→ ... === End of paragraphs === B.2.4 NER Task: Count how many times the entity "PERSON" appears in each sentence and provide the total count. ,→ ,→ Background: - An entity may consist of multiple words that form a contiguous fragment in the text ,→ ,→ - You need to first identify entities in each sentence (named entity recognition), then count them ,→ ,→ - Two entities may appear consecutively without punctuation or words between them ,→ ,→ - No entity overlaps occur (each word belongs to at most one entity),→ - Some words do not belong to any entity Entity Definition: - PERSON: names of people, real or fictional, but not nominals,→ Instructions: - Identify all PERSON entities in each sentence,→ - Count the number of PERSON entity mentions in each sentence separately,→ - Provide the count for each sentence along with the total count across all sentences ,→ ,→ - Each distinct mention counts as one occurrence, even if it refers to the same person ,→ ,→ Response format: Return a JSON object with: - One key per sentence: "1", "2", "3", . . . , mapping to the integer count of PERSON mentions in that sentence ,→ ,→ - "total": total count of PERSON entities across all sentences,→ - "reasoning": brief explanation of how you identified and counted the PERSON entities ,→ ,→ Example: "1": 0, "2": 2, "3": 1, "total": 3, "reasoning": "your approach here",→ === Here are the sentences === Sentence 1: we love everything about the fence .,→ Sentence 2: i want to hook up with that girl paige in the brown leather jacket . ,→ ,→ Sentence 3: in addition , there is a reduction of 22,101 mmbtu which is the difference between the scada values ( best available ) that anita showed on the february 29th storage sheet and the " official " february 29th values that gary wilson received from mips . ,→ ,→ ,→ ,→ ,→ ,→ ,→ ... === End of sentences === B.2.5 Parity Task: For each number, identify whether it is odd or even, then provide summary counts for both categories. ,→ ,→ 21 Background: - An odd number is an integer that is not evenly divisible by 2,→ - Odd numbers end in 1, 3, 5, 7, or 9 (label 1),→ - An even number is an integer that is evenly divisible by 2,→ - Even numbers end in 0, 2, 4, 6, or 8 (label 0),→ Instructions: - Check each number to determine if it is odd or even,→ - Classify each number using the labels: * 1 = odd * 0 = even - Provide the classification for each individual number,→ - Also provide summary counts for both odd and even categories,→ Response format: Return a JSON object with: - One key per number: "1", "2", "3", . . . , mapping to the classification (0 or 1) ,→ ,→ - "odd": integer count of numbers classified as odd,→ - "even": integer count of numbers classified as even,→ - "reasoning": brief explanation of your approach,→ Example for 5 numbers: "1": 0, "2": 1, "3": 0, "4": 1, "5": 1, "odd": 3, "even": 2, "reasoning": "your approach here" ,→ ,→ === Here are the numbers === Number 1: 18010 Number 2: 10160 Number 3: 89449 ... === End of numbers === B.2.6 Sentiment Task: For each movie review, classify whether it is positive or negative, then provide summary counts. ,→ ,→ Instructions: - Classify each review as either: - 0 = negative sentiment - 1 = positive sentiment - Provide the classification for each individual review,→ - Also provide summary counts for negative and positive reviews,→ Response format: Return a JSON object with: - One key per review: "1", "2", "3", . . . , mapping to the classification (0 or 1) ,→ ,→ - "negative": integer count of reviews classified as negative,→ - "positive": integer count of reviews classified as positive,→ - "reasoning": brief explanation of your approach to classification,→ Example for 3 reviews: "1": 1, "2": 0, "3": 1, "negative": 1, "positive": 2, "reasoning": "your approach here" ,→ ,→ === Here are the movie reviews === Review 1: High Crimes is a cinematic misdemeanor , a routine crime thriller remarkable only for its lack of logic and misuse of two fine actors , Morgan Freeman and Ashley Judd . ,→ ,→ ,→ ,→ ,→ Review 2: One of the worst movies of the year .,→ Review 3: A mix of gritty realism , crisp storytelling and radiant compassion that effortlessly draws you in . ,→ ,→ ,→ ... === End of movie reviews === B.2.7 Word Task: For each tweet, count how many times the word "women" appears, then provide the total count. ,→ ,→ Instructions: - Search is case-insensitive (e.g., "women", "Women", "WOMEN" all count),→ - Count occurrences that include the substring "women" (e.g., "women", "womens", "women's", "womenfolk") ,→ ,→ - Do not count forms that lack the substring "women" (e.g., "woman", "womankind") ,→ ,→ 22 - Count occurrences in each tweet separately,→ - Provide the per-tweet counts plus the overall total,→ Response format: Return a JSON object with: - One key per tweet: "1", "2", "3", . . . , mapping to the count of "women" in that tweet (integer) ,→ ,→ - "total": integer representing the total count of "women" across all tweets ,→ ,→ - "reasoning": brief explanation of your counting approach,→ Example for 3 tweets: "1": 2, "2": 0, "3": 1, "total": 3, "reasoning": "your approach here",→ === Here are the tweets === Tweet 1: IF FEMINISTS WERE HONEST "I want a worldwide matriarchal dictatorship with all men enslaved to women" \#GamerGate \#SemST ,→ ,→ ,→ Tweet 2: What the fuck do women even do? I mean seriously they're just useless other than sex. \#womensrights \#Feminist \#SemST ,→ ,→ ,→ Tweet 3: DEAR FEMINISTS Start asking for accountability from man-haters instead of shielding them for convenient concealment. \#SemST ,→ ,→ ,→ ... === End of tweets === B.2.8 WSD Task: For each paragraph, identify whether the word "apple" refers to the company or the fruit, then provide total counts. ,→ ,→ ,→ Background: - Each paragraph contains exactly one occurrence of the word "apple" (case-insensitive, as a complete word, not as part of another word) ,→ ,→ ,→ - This "apple" can mean either: * The company (label 0): Apple Inc., the technology company,→ * The fruit (label 1): the edible fruit that grows on apple trees,→ - You need to determine the meaning of "apple" in each paragraph based on context ,→ ,→ Instructions: - Read each paragraph carefully and classify the meaning of "apple",→ - For each paragraph, assign: * 0 if "apple" means the company (Apple Inc.),→ * 1 if "apple" means the fruit - Count the total number of paragraphs for each category,→ - Provide classification for each paragraph along with summary counts,→ Response format: Return a JSON object with: - One key per paragraph: "1", "2", "3", . . . , mapping to either 0 (company) or 1 (fruit) ,→ ,→ - "company": integer count of paragraphs where "apple" means the company,→ - "fruit": integer count of paragraphs where "apple" means the fruit,→ - "reasoning": brief explanation of your approach to word sense disambiguation ,→ ,→ Example for 3 paragraphs: "1": 0, "2": 1, "3": 0, "company": 2, "fruit": 1, "reasoning": "your approach here" ,→ ,→ === Here are the paragraphs === Paragraph 1: both seasons are available for download from apple's itunes store . ,→ ,→ Paragraph 2: in klayman i , the plaintiffs sued the same government defendants and in addition , facebook , yahoo! , google , microsoft , youtube , aol , paltalk , skype , sprint , at\&t , apple again alleging the bulk metadata collection violates the first , fourth and fifth amendment and constitutes divulgence of communication records in violation of section 2702 of stored communications act . ,→ ,→ ,→ ,→ ,→ ,→ ,→ ,→ ,→ ,→ ,→ ,→ 23 TaskAgreement (%) BShift69.3 SubjNum82.5 Voice78.3 Table 5: Task filtering across tasks that have been re- moved. Paragraph 3: description alongside dried pears the filling also contains raisin , walnut and other dried fruit such as apple or figs . ,→ ,→ ,→ ... === End of paragraphs === C Single Instance Filtering Results We note that not all models in our evaluation are included in this SIP filtering analysis, as the filter- ing procedure is defined based on a fixed subset of comparison models; however, the excluded models generally exhibit stronger performance in the MIP setting, and are likely to perform similarly under the SIP settings (e.g., for this filtering, we used the smaller versions of the closed-source LLMs considered). C.1 Individual Results Table 5 reports the agreements for the tasks that are removed, while Table 6 shows the average SIP suc- cess rate for each model and task. Although BShift achieves a relatively high SIP success rate for the selected models, its agreement across models is low. C.2 Task Filtering Results Table 7 shows the retained instance percentage for each task, along with the corresponding maximum and minimum SIP success rates across models. D Experimental Results Here we present the success rate and failure break- down for each model and task. D.1 Success Rate D.1.1 Task Success Rate for Models Figure 8, Figure 9, Figure 10 and Figure 11 show task success rate for each model. D.1.2 Model Success Rate for Tasks Figure 12 and Figure 13 show model success rate for each task. Model Arithmetic Language NER News Parity BShift SubjNum Sentiment Tweets Voice WSD Average DeepSeek V3 98.3 99.2 95.8 97.6 100.0 92.7 88.3 99.3 99.6 89.5 99.4 96.3 gpt-oss-120b 97.2 99.5 96.2 97.6 100.0 92.6 89.4 98.5 100.0 91.4 99.3 96.5 gpt-oss-20b 97.7 99.5 96.2 97.2 100.0 90.4 89.6 97.8 100.0 90.6 99.1 96.2 Llama 3.3 93.7 99.5 93.6 98.4 100.0 90.9 87.4 99.7 99.5 86.9 99.2 95.3 Llama 4 Maverick 96.7 99.3 94.3 99.2 100.0 90.9 88.9 99.4 99.9 91.7 99.4 96.3 Llama 4 Scout 93.4 97.9 93.9 97.2 100.0 86.9 87.3 99.0 99.5 88.7 99.1 94.8 Mistral NeMo 72.0 96.2 78.1 96.8 75.3 62.9 75.2 83.8 60.3 72.7 98.4 79.2 Qwen3-Instruct 99.5 99.4 97.3 99.2 100.0 91.3 88.9 99.5 99.7 92.8 99.3 97.0 Gemini 2.5 Flash 96.2 99.6 96.5 98.0 100.0 92.8 88.9 99.0 99.4 92.0 99.4 96.5 GPT-5 Nano 98.0 99.5 96.5 97.2 100.0 93.0 89.0 99.2 100.0 91.3 99.2 96.6 Grok 4 Fast 97.9 99.5 97.2 98.8 100.0 95.7 88.6 99.5 100.0 90.2 99.4 97.0 Table 6: SIP success rate (%) across tasks. Open-weight models are listed first, followed by closed-source models. Underlined rows and columns indicate the tasks and LLMs that are excluded because they do not satisfy the filtering criteria described in Section 3.2. 24 Task Agreement (%) Max (%) Min (%) Arithmetic89.099.593.7 Category94.899.297.2 Language98.899.699.2 NER87.697.393.6 Parity100.0100.0100.0 Sentiment96.499.797.8 Word98.3100.099.4 WSD98.699.499.1 Table 7: Task filtering results showing agreement (i.e., the percentage of instances for which all LLMs produce correct SIP predictions), as well as the maximum and minimum SIP success rates across all LLMs (the actual agreement and minimum rate for Parity is 99.96%). D.2 Failure Breakdown D.2.1 Failure Breakdown for Models Figure 14, Figure 15 and Figure 16 show failure breakdown for models, averaged across all tasks. D.2.2 Failure Breakdown for Tasks Figure 17 and Figure 18 show failure breakdown for tasks, averaged across all models. D.3 Context Length D.3.1 Default and Augmented Success Rate Figure 19 compares average performance across all tasks and models between the default and arti- ficially augmented settings, as the context length increases. D.3.2 Default and Augmented Success Rate for Models Figure 20, Figure 21 and Figure 22 show task suc- cess rate for each model. D.3.3 Default and Augmented Success Rate for Tasks Figure 23 and Figure 24 show model success rate for each task. 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate DeepSeek R1 Arithmetic Category Language NER Parity Sentiment Word WSD 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate DeepSeek V3 Arithmetic Category Language NER Parity Sentiment Word WSD 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate gpt-oss-120b Arithmetic Category Language NER Parity Sentiment Word WSD 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate gpt-oss-20b Arithmetic Category Language NER Parity Sentiment Word WSD Figure 8: Success rate of models. 25 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Llama 3.3 Arithmetic Category Language NER Parity Sentiment Word WSD 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Llama 4 Maverick Arithmetic Category Language NER Parity Sentiment Word WSD 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate MiniMax M2.5 Arithmetic Category Language NER Parity Sentiment Word WSD 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Qwen3-Instruct Arithmetic Category Language NER Parity Sentiment Word WSD Figure 9: Success rate of models. 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Qwen3-Thinking Arithmetic Category Language NER Parity Sentiment Word WSD 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Claude Sonnet 4.6 Arithmetic Category Language NER Parity Sentiment Word WSD 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Gemini 2.5 Flash Arithmetic Category Language NER Parity Sentiment Word WSD 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Gemini 3.1 Pro Arithmetic Category Language NER Parity Sentiment Word WSD Figure 10: Success rate of models. 26 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate GPT-5 Arithmetic Category Language NER Parity Sentiment Word WSD 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate GPT-5 Nano Arithmetic Category Language NER Parity Sentiment Word WSD 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Grok 4 Arithmetic Category Language NER Parity Sentiment Word WSD 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Grok 4 Fast Arithmetic Category Language NER Parity Sentiment Word WSD Figure 11: Success rate of models. 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Arithmetic DeepSeek R1 DeepSeek V3 gpt-oss-120b gpt-oss-20b Llama 3.3 Llama 4 Maverick MiniMax M2.5 Qwen3-Instruct Qwen3-Thinking Claude Sonnet 4.6 Gemini 2.5 Flash Gemini 3.1 Pro GPT-5 GPT-5 Nano Grok 4 Grok 4 Fast 25102050100200 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Category DeepSeek R1 DeepSeek V3 gpt-oss-120b gpt-oss-20b Llama 3.3 Llama 4 Maverick MiniMax M2.5 Qwen3-Instruct Qwen3-Thinking Claude Sonnet 4.6 Gemini 2.5 Flash Gemini 3.1 Pro GPT-5 GPT-5 Nano Grok 4 Grok 4 Fast 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Language DeepSeek R1 DeepSeek V3 gpt-oss-120b gpt-oss-20b Llama 3.3 Llama 4 Maverick MiniMax M2.5 Qwen3-Instruct Qwen3-Thinking Claude Sonnet 4.6 Gemini 2.5 Flash Gemini 3.1 Pro GPT-5 GPT-5 Nano Grok 4 Grok 4 Fast 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate NER DeepSeek R1 DeepSeek V3 gpt-oss-120b gpt-oss-20b Llama 3.3 Llama 4 Maverick MiniMax M2.5 Qwen3-Instruct Qwen3-Thinking Claude Sonnet 4.6 Gemini 2.5 Flash Gemini 3.1 Pro GPT-5 GPT-5 Nano Grok 4 Grok 4 Fast Figure 12: Model success rate for tasks. 27 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Parity DeepSeek R1 DeepSeek V3 gpt-oss-120b gpt-oss-20b Llama 3.3 Llama 4 Maverick MiniMax M2.5 Qwen3-Instruct Qwen3-Thinking Claude Sonnet 4.6 Gemini 2.5 Flash Gemini 3.1 Pro GPT-5 GPT-5 Nano Grok 4 Grok 4 Fast 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Sentiment DeepSeek R1 DeepSeek V3 gpt-oss-120b gpt-oss-20b Llama 3.3 Llama 4 Maverick MiniMax M2.5 Qwen3-Instruct Qwen3-Thinking Claude Sonnet 4.6 Gemini 2.5 Flash Gemini 3.1 Pro GPT-5 GPT-5 Nano Grok 4 Grok 4 Fast 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Word DeepSeek R1 DeepSeek V3 gpt-oss-120b gpt-oss-20b Llama 3.3 Llama 4 Maverick MiniMax M2.5 Qwen3-Instruct Qwen3-Thinking Claude Sonnet 4.6 Gemini 2.5 Flash Gemini 3.1 Pro GPT-5 GPT-5 Nano Grok 4 Grok 4 Fast 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate WSD DeepSeek R1 DeepSeek V3 gpt-oss-120b gpt-oss-20b Llama 3.3 Llama 4 Maverick MiniMax M2.5 Qwen3-Instruct Qwen3-Thinking Claude Sonnet 4.6 Gemini 2.5 Flash Gemini 3.1 Pro GPT-5 GPT-5 Nano Grok 4 Grok 4 Fast Figure 13: Model success rate for tasks. 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 2.5%2.5%2.5% 5.0% 2.5% 5.0% 5.0% 7.5% 2.5% 15.0% 17.5% 15.0% 2.5% 5.0% 2.5% 27.5% 10.0% 17.5% 2.5% 5.7% 2.9% 51.4% 14.3% 22.9% 2.9% 22.9% 8.6% 45.7% 11.4% 11.4% 20.0% 22.9% 48.6% 8.6% DeepSeek R1 Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 7.5% 10.0% 7.5% 10.0% 10.0% 7.5% 12.5% 22.5% 5.0% 5.0% 5.0% 42.5% 2.5% 17.5% 7.5% 65.0% 42.5% 2.5% 52.5% 62.5% 35.0% 71.4% 28.6% 14.3% 65.7% 11.4% 8.6% 14.3% 62.9% 22.9% DeepSeek V3 Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 5.0%5.0% 2.5% 5.0% 2.5%17.5% 2.5% 5.0% 30.0%40.0% 2.5% 2.5% 2.9% 11.4% 17.1% 40.0% 2.9% 14.3% 42.9% 20.0% 11.4% 11.4% 14.3% 48.6% 5.7% 8.6% 22.9% gpt-oss-120b Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 2.5%2.5% 2.5%7.5% 2.5% 5.0% 5.0% 10.0% 5.0% 2.5% 2.5% 42.5% 10.0% 10.0% 10.0% 42.5% 5.0% 7.5% 2.9% 45.7% 20.0% 17.1% 5.7% 14.3% 42.9% 8.6% 5.7% 28.6% 14.3% 54.3% 31.4% gpt-oss-20b Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error Figure 14: Failure breakdown for models. 28 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 5.0% 2.5% 2.5% 2.5% 10.0% 2.5% 5.0% 2.5% 12.5% 10.0% 15.0% 20.0% 5.0% 45.0% 42.5% 10.0% 42.5% 70.0% 5.0% 15.0% 7.5% 2.5% 75.0% 5.0% 2.5% 15.0% 2.9% 11.4% 65.7% 2.9% 2.9% 14.3% 14.3% 22.9% 45.7% 17.1% 14.3% 25.7% 22.9% 37.1% Llama 3.3 Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 2.5% 2.5% 5.0% 7.5% 5.0% 7.5% 12.5% 5.0% 25.0% 2.5% 25.0% 5.0% 45.0% 7.5% 47.5% 7.5% 35.0% 2.5% 57.5% 2.5% 32.5% 7.5% 8.6% 60.0% 5.7% 5.7% 20.0% 2.9% 74.3% 22.9% 2.9% 22.9% 74.3% Llama 4 Maverick Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 2.5% 5.0% 2.5%2.5% 2.5% 7.5% 2.5% 10.0% 5.0% 2.5% 12.5% 12.5% 20.0% 2.5% 5.0% 17.5% 15.0% 37.5% 15.0% 7.5% 10.0% 2.5% 82.9% 8.6% 2.9% 2.9% 77.1% 17.1% 2.9% 2.9% 88.6% 2.9% 8.6% MiniMax M2.5 Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 2.5%2.5% 2.5% 12.5% 2.5% 12.5% 10.0% 2.5% 7.5% 10.0% 47.5% 2.5% 20.0% 10.0% 60.0% 52.5% 47.5% 70.0% 30.0% 62.9% 37.1% 85.7% 14.3% 14.3% 17.1% 54.3% 14.3% Qwen3-Instruct Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error Figure 15: Failure breakdown for models. 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 2.5% 7.5% 2.5% 5.0% 12.5% 2.5% 2.5% 7.5% 12.5% 10.0% 7.5% 15.0% 10.0% 20.0% 11.4% 37.1% 8.6% 20.0% 5.7% 28.6% 45.7% 2.9% 20.0% 31.4% 8.6% 54.3% 2.9% 2.9% Qwen3-Thinking Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 7.5%7.5% 15.0% 2.5% 2.5% 35.0% 5.0% 60.0% 25.0% 5.0% 62.5% 20.0% 35.0% 2.5% 40.0% 28.6% 42.9% 28.6% 31.4% 48.6% 20.0% 97.1% 2.9% Gemini 2.5 Flash Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 7.5% 5.0% 2.5%2.5% 10.0% 5.0% 30.0% 2.5% 40.0% 7.5% 2.5% 68.6% 2.9% 8.6% 11.4% 68.6% 2.9% 28.6% 14.3% 48.6% 37.1% GPT-5 Nano Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 2.5%2.5% 5.0% 7.5% 2.5% 7.5% 15.0% 17.5% 20.0% 7.5% 22.5% 51.4% 11.4% 17.1% 71.4% 5.7% 5.7% 14.3% 77.1% 5.7% 17.1% Grok 4 Fast Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error Figure 16: Failure breakdown for models. 29 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 3.3% 25.0% 3.3% 28.3% 8.3% 40.0% 20.0% 33.3% 6.7% 23.3% 51.7% 8.3% 5.0% 33.3% 36.7% 3.3% 8.3% 30.0% 48.3% 3.3% 10.0% 6.7% 36.7% 46.7% 10.0% 10.0% 51.7% 16.7% 21.7% Arithmetic Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error 25102050100200 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 8.3% 6.7% 10.0% 3.3% 15.0% 20.0% 8.3% 25.0% 13.3% 15.0% 41.7% 43.3% 5.0% 46.7% 45.0% 5.0% 3.3% 3.3% 63.3% 18.3% 13.3% Category Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 3.3% 5.0% 16.7% 6.7% 3.3% 33.3% 16.7% 5.0% 26.7% 3.3% 33.3% 28.3% 13.3% 6.7% 50.0% 28.3% 11.7% 16.7% 10.0% 56.7% 8.3% 8.3% 58.3% 3.3% 20.0% 18.3% 75.0% 6.7% 3.3% 15.0% Language Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 3.3% 6.7%10.0% 15.0% 3.3% 10.0% 11.7% 3.3% 21.7% 20.0% 6.7% 8.3% 5.0% 31.7% 21.7% 10.0% 13.3% 48.3% 13.3% 8.3% 8.3% 15.0% 61.7% 13.3% 8.3% 26.7% 41.7% 5.0% 18.3% NER Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error Figure 17: Failure breakdown for tasks. 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 10.0% 6.7% 3.3% 13.3% 31.7% 6.7% 31.7% 10.0% 31.7% 3.3% 6.7% 8.3% 11.7% 6.7% 38.3% 10.0% 25.0% 11.7% 3.3% 38.3% 8.3% 8.3% 33.3% 26.7% 13.3% 18.3% Parity Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 26.7% 41.7% 18.3% 20.0% 31.7% 5.0% 23.3% 16.7% 26.7% 5.0% 20.0% 45.0% 6.7% 16.7% 5.0% 23.3% 58.3% 11.7% 8.3% 33.3% 40.0% 18.3% Sentiment Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 6.7% 3.3% 5.0% 11.7% 5.0% 3.3% 31.7% 3.3% 3.3% 5.0% 33.3% 15.0% 3.3% 3.3% 10.0% 11.7% 43.3% 23.3% 3.3% 11.7% 13.3% 58.3% 6.7% 8.3% 15.0% 28.3% 40.0% 16.7% Word Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error 2510205010020050010002000 Number of Instances 0% 20% 40% 60% 80% 100% Failure Rate 6.7% 16.7% 3.3% 41.7% 8.3% 5.0% 43.3% 15.0% 11.7% 38.3% 3.3% 6.7% 15.0% 30.0% 6.7% 35.0% 3.3% 8.3% 11.7% 51.7% 8.3% 20.0% 6.7% 10.0% 36.7% 46.7% WSD Key Mistake Aggregation Mistake Individual Mistake Agg. + Indi. Mistake Parsing Error Overlong Input Error Figure 18: Failure breakdown for tasks. 30 2005001K2K5K10K20K50K100K200K Context Length (Total Prompt Tokens) 0% 20% 40% 60% 80% 100% Success Rate Default Augmented 200 400 600 800 1000 Number of Instances Figure 19: Success rate (lines) and the number of in- stances (bars) in the artificial length setting as total prompt token length increases. Error bars indicate stan- dard deviation across five random seeds. 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate DeepSeek R1 Default Augmented 0 20K 40K 60K 80K 100K Context Length 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate DeepSeek V3 Default Augmented 0 20K 40K 60K 80K 100K Context Length 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate gpt-oss-120b Default Augmented 0 20K 40K 60K 80K 100K Context Length 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate gpt-oss-20b Default Augmented 0 20K 40K 60K 80K 100K Context Length Figure 20: Success rate of models. 31 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Llama 3.3 Default Augmented 0 20K 40K 60K 80K 100K Context Length 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Llama 4 Maverick Default Augmented 0 50K 100K 150K 200K 250K Context Length 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate MiniMax M2.5 Default Augmented 0 25K 50K 75K 100K 125K 150K 175K 200K Context Length 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Qwen3-Instruct Default Augmented 0 50K 100K 150K 200K Context Length Figure 21: Success rate of models. 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Qwen3-Thinking Default Augmented 0 50K 100K 150K 200K Context Length 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Gemini 2.5 Flash Default Augmented 0 50K 100K 150K 200K 250K Context Length 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate GPT-5 Nano Default Augmented 0 50K 100K 150K 200K Context Length 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Grok 4 Fast Default Augmented 0 50K 100K 150K 200K 250K Context Length Figure 22: Success rate of models. 32 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Arithmetic Default Augmented 0 25K 50K 75K 100K 125K 150K 175K 200K Context Length 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Category Default Augmented 0 10K 20K 30K 40K 50K Context Length 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Language Default Augmented 0 50K 100K 150K 200K 250K 300K 350K Context Length 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate NER Default Augmented 0 50K 100K 150K 200K Context Length Figure 23: Success rate for tasks. 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Sentiment Default Augmented 0 50K 100K 150K 200K Context Length 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate Word Default Augmented 0 50K 100K 150K 200K Context Length 251020501002005001000 Number of Instances 0% 20% 40% 60% 80% 100% Success Rate WSD Default Augmented 0 50K 100K 150K 200K 250K Context Length Figure 24: Success rate for tasks. 33