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Training-Free Agentic AI: Probabilistic Control and Coordination in Multi-Agent LLM Systems
Mohammad Parsa Hosseini, Ankit Shah, Saiyra Qureshi, Alex Huang, Connie Miao, Wei Wei
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Summary
The paper introduces REDEREF, a training-free controller for multi-agent LLM systems that improves routing efficiency during recursive delegation. It utilizes belief-guided delegation via Thompson sampling, reflection-driven re-routing, evidence-based selection, and memory-aware priors. Experiments show REDEREF reduces token usage by 28%, agent calls by 17%, and time-to-success by 19% compared to random recursive delegation, while maintaining task success rates.
Entities (7)
Relation Signals (7)
REDEREF ā uses ā Thompson Sampling
confidence 95% Ā· REDEREF integrates (i) belief-guided delegation via Thompson sampling to prioritize agents with historically positive marginal contributions
REDEREF ā comparedto ā random recursive delegation
confidence 90% Ā· compared to random recursive delegation
REDEREF ā evaluatedon ā Split-Knowledge Tasks
confidence 90% Ā· Across multi-agent split-knowledge tasks, we show that...
REDEREF ā reduces ā time-to-success
confidence 90% Ā· belief-guided routing reduces ... time-to-success by 19%
REDEREF ā reduces ā Token usage
confidence 90% Ā· belief-guided routing reduces token usage by 28%
REDEREF ā reduces ā agent calls
confidence 90% Ā· belief-guided routing reduces ... agent calls by 17%
REDEREF ā outperforms ā AutoGen
confidence 75% Ā· In contrast, REDEREF performs online belief-guided delegation without retraining, maintaining efficiency and decentralization.
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Abstract
Abstract:Multi-agent large language model (LLM) systems enable complex, long-horizon reasoning by composing specialized agents, but practical deployment remains hindered by inefficient routing, noisy feedback, and high interaction cost. We introduce REDEREF, a lightweight and training-free controller for multi-agent LLM collaboration that improves routing efficiency during recursive delegation. REDEREF integrates (i) belief-guided delegation via Thompson sampling to prioritize agents with historically positive marginal contributions, (ii) reflection-driven re-routing using a calibrated LLM or programmatic judge, (iii) evidence-based selection rather than output averaging, and (iv) memory-aware priors to reduce cold-start inefficiency. Across multi-agent split-knowledge tasks, we show that while recursive retry alone saturates task success, belief-guided routing reduces token usage by 28%, agent calls by 17%, and time-to-success by 19% compared to random recursive delegation, and adapts gracefully under agent or judge degradation. These results demonstrate that simple, interpretable probabilistic control can meaningfully improve the efficiency and robustness of multi-agent LLM systems without training or fine-tuning.
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- Source: https://arxiv.org/abs/2603.13256v1
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Training-Free Agentic AI: Probabilistic Control and Coordination in Multi-Agent LLM Systems Mohammad Parsa Hosseini * 1 Ankit Shah * 1 Saiyra Qureshi 1 Alex Huang 1 Connie Miao 1 Wei Wei 1 Abstract Multi-agent large language model (LLM) sys- tems enable complex, long-horizon reasoning by composing specialized agents, but practical de- ployment remains hindered by inefficient routing, noisy feedback, and high interaction cost. We introduce REDEREF, a lightweight and training- free controller for multi-agent LLM collabora- tion that improves routing efficiency during recur- sive delegation. REDEREF integrates (i) belief- guided delegation via Thompson sampling to pri- oritize agents with historically positive marginal contributions, (i) reflection-driven re-routing us- ing a calibrated LLM or programmatic judge, (i) evidence-based selection rather than output aver- aging, and (iv) memory-aware priors to reduce cold-start inefficiency. Across multi-agent split- knowledge tasks, we show that while recursive retry alone saturates task success, belief-guided routing reduces token usage by 28%, agent calls by 17%, and time-to-success by 19% compared to random recursive delegation, and adapts grace- fully under agent or judge degradation. These re- sults demonstrate that simple, interpretable prob- abilistic control can meaningfully improve the efficiency and robustness of multi-agent LLM sys- tems without training or fine-tuning. 1. Introduction Large Language Models (LLMs) such as GPT-4, Gemini, and Claude have evolved from narrow text-completion tools into broadly capable reasoning engines, surpassing human performance on tasks ranging from legal exams (OpenAI, 2023) to software engineering challenges (Jimenez et al., 2024). However, most of these benchmarks are single-turn interactions. Real-world deployments, in contrast, demand persistence and adaptability: evolving software reposito- * Equal contribution 1 Accenture.Correspondence to: Parsa Hosseini<parsa.hosseini@accenture.com>, Ankit Shah <ankit.parag.shah@accenture.com>. Preprint. March 17, 2026. ries over weeks, synthesizing iterative scientific reviews, or mediating multistakeholder corporate decisions. These are inherently multiturn, long-horizon, and collaborative, push- ing beyond what any single monolithic model, no matter how large, can reliably achieve. Multi-agent LLM systems have emerged as a promising direction to scale intelligence by composing the comple- mentary skills of multiple agents. For example, one agent might specialize in writing unit tests, another in literature surveys, and a third in policy analysis. By enabling interac- tion between such experts, these systems can address tasks outside the scope of any individual model. Yet, their deploy- ment remains hampered by three persistent bottlenecks: (1) Dynamic task routing. Existing orchestrators often rely on fixed pipelines or static vector similarity rules. These approaches are brittle: When task requirements change or agent performance degrades, the system continues to mis- route, invoking wrong experts, and compounding errors. (2) Credit assignment across long horizons. In extended dialogues, failures may not be visible until dozens of turns later. Without timely and fine-grained feedback, the sys- tem cannot effectively demote underperforming agents or up-weight reliable ones, leading to stagnation in routing efficiency. (3) Cold-start inefficiency. When a new task arrives, the system has no prior evidence about which agents are com- petent. Without mechanisms to transfer knowledge from previous interactions, early routing is effectively random, wasting tokens and agent calls before the system can differ- entiate agent quality. We propose REDEREF, a lightweight and training-free controller for multi-agent LLM systems. REDEREF wraps any pool of agents with four components: (1) belief-guided delegation via Thompson sampling to prioritize agents with historically positive marginal contributions; (2) calibrated reflection via a judge that triggers credit assignment and re-routing; (3) evidence-checked selection (rather than av- eraging); and (4) memory-aware priors to reduce cold-start inefficiency and context bloat. By combining these elements into a recursive loop, RED- 1 arXiv:2603.13256v1 [cs.CL] 24 Feb 2026 Training-Free Agentic AI for Multi-Agent LLM Systems EREF enables efficient, belief-guided routing across a pool of heterogeneous agents. In controlled experiments on split- knowledge tasks, we show that belief-guided routing re- duces token usage by 28%, agent calls by 17%, and time-to- success by 19% compared to an otherwise identical system with uniform random selection, while maintaining matched task success rates. Contributions. We make the following contributions: ā¢We introduce REDEREF, a training-free controller for multi-agent LLM systems that improves routing efficiency under recursive retry without requiring fine- tuning or centralized training. ā¢We reinterpret belief updates as modeling an agentās probability of providing a positive marginal contri- bution, resolving credit assignment in compositional multi-agent tasks. ā¢We demonstrate empirically that belief-guided delega- tion substantially reduces token usage, agent calls, and time-to-success compared to random recursive delega- tion at matched success rates. ⢠We analyze robustness to agent impairment and judge miscalibration, showing graceful degradation rather than catastrophic routing failures. 2. Related Work Reasoning, reflection, and search. Methods such as ReAct (Yao et al., 2023b), Self-Refine (Madaan et al., 2023), Reflexion (Shinn et al., 2023), and Tree-of-Thoughts (ToT) (Yao et al., 2023a) improve reasoning by coupling tool use, iterative self-feedback, episodic memory, or back- tracking search. Agent-R (Yuan et al., 2025) and recent surveys (Guo et al., 2024) highlight reflection as central to multi-agent LLMs. Unlike these approaches, REDEREF uses an explicit probabilistic controller: Thompson sam- pling delegates under uncertainty, while binary judge out- comes update interpretable Beta posteriors that drive re- routing. Orchestration, ensembles, and routing. Frameworks such as AutoGen (Wu et al., 2023) coordinate agents via scripted protocols, and Mixture-of-Agents (MoA) (Wang et al., 2024) aggregate outputs via ensembles. Early or- chestrators (e.g., LangChain graphs, AutoGPT workflows) hard-code pipelines, while systems like RopMura (Wu et al., 2025), DyLAN (Liu et al., 2024), and MLPO (Li et al., 2025b) introduce dynamic routing with agent team optimiza- tion. In contrast, REDEREF performs online belief-guided delegation without retraining, maintaining efficiency and decentralization. Learning-based coordination. Multi-agent reinforce- ment learning has long addressed coordination (Lowe et al., 2017; Foerster et al., 2018), with adaptations for LLMs such as SWEET-RL (Zhou et al., 2025). Yet RL methods are sample-hungry. Probabilistic approaches, e.g., Bayesian Delegation (Wu et al., 2021), estimate expertise from sparse data. REDEREF combines Thompson sampling with reflection-driven control, cooldown-based exploration, and memory-aware priors in a unified, training-free orchestra- tion loop. Benchmarks and positioning.Public environments (We- bArena (Zhou et al., 2024), Mind2Web (Deng et al., 2023), GAIA (Mialon et al., 2024), SWE-bench (Jimenez et al., 2024)) highlight the difficulty of real-world, long-horizon tasks (e.g., GPT-4 achievesā¼14% on WebArena vs. humans atā¼78%). Against this backdrop, REDEREF contributes a training-free adaptive controller that combines belief-guided delegation, embedded reflection and memory to improve efficiency, robustness and interpretability over static, ensem- ble or RL-based approaches. 3. The REDEREF Framework We formalize multi-agent coordination as a training-free probabilistic control loop. Given a taskTwith queryqand a population ofNheterogeneous agentsA =A 1 ,...,A N , each agentA i possesses an unobserved task-conditional competenceĪø i ā [0, 1]. The controller maintains a Beta pos- teriorĪø i ā¼ Beta(α i ,β i ), updated online from binary feed- backy ā0, 1indicating success or failure in the evaluated results. Unless otherwise stated, priors areα 0 = β 0 = 1 (uninformative) or initialized by the memory-aware scheme in Section 3.6. The overall decision-making pipeline of REDEREF, including belief-guided delegation, recursive reflection, and memory-based adaptation, is illustrated in Figure 1. This flowchart highlights how success cases are propagated through posterior updates and memory, whereas failures trigger refinement, aggregation, and rerouting until a satisfactory solution is produced. Unlike standard bandit formulations, REDEREF operates over compositional multi-agent reasoning trajectories where rewards are delayed, aggregated, and non-attributable to individual actions. Interpretation of Agent Beliefs.The belief parameterĪø i does not represent the probability that agentA i can inde- pendently solve the task. Instead,Īø i models the probability that invoking agentA i at the current recursion step yields a net-positive marginal contribution relative to the current candidate set. This aligns Bernoulli feedback with compo- sitional multi-agent tasks and avoids counterfactual blame assignment to individual agents. 2 Training-Free Agentic AI for Multi-Agent LLM Systems User Query q Belief-Guided Delegation (Thompson Sampling) Selected Agent A i ā LLM + Programmatic Judge Success? Update Posterior & Store in Memory Refine Query & Re-route Aggregate Candidates (Selection + Evidence) Final Answer Figure 1. System architecture of REDEREF. Queries pass through belief-guided delegation, agent execution, and judge evaluation. Upon success (top path), the posterior is updated and stored in memory before producing the final answer. Upon failure (bottom path), the query is refined and re-routed, with candidates aggregated using evidence-based selection. 3.1. Belief-Guided Delegation via Thompson Sampling (Core Policy) At recursion depthdfor queryq d , REDEREF treats agent selection as a multi-armed bandit problem and applies Thompson sampling: Ė Īø i ā¼ Beta(α i ,β i ), i ā ā arg max i Ė Īø i .(1) The selected agentA i ā proposes a candidate solution. After judging, the posterior updates are in closed form: α i ā ā α i ā + y, β i ā ā β i ā + (1ā y),(2) wherey = I[success]. Thompson sampling provides a prin- cipled explorationāexploitation trade-off: agents with higher posterior means are preferred while uncertainty induces ex- ploration. We denote the posterior mean as μ i = α i α i +β i . 3.2. Self-Reflection and Judging Each candidate is evaluated by a judgeJwho delivers a calibrated binary verdictE āSUCCESS, FAILURE. Two evidence channels are integrated: 1. Programmatic metrics, when available (e.g., EM / F1, supporting facts F1, unit test pass rate), which short- circuit the success of unambiguous positives. 2. LLM adjudication, which produces a binary decision and a brief rationale when the metrics are absent or inconclusive. We calibrateJon a small labeled set (Nā 200) to estimate FP/FN rates and set thresholds. The verdict is mapped to the Bernoulli feedback driving Bayesian updates: y = I[E = SUCCESS]. This makes reflection the engine of both credit assignment (posterior updates) and control (whether to re-route). 3.3. Text-Appropriate Aggregation REDEREF aggregates by selection with evidence, not av- eraging. We construct a set of candidates with rationales, score them using task metrics or retrieval-grounded entail- ment checks (Li et al., 2025a), optionally run a bounded debate (up to two refinement turns) among top candidates, and select the best-supported answer. For structured outputs (e.g., numeric fields, dates, JSON), we extract atomic fields, fuse them via competence- weighted voting usingμ i = α i /(α i + β i )as trust weights, then regenerate a coherent output. This modality-aware design yields robustness across open-ended and structured tasks while maintaining interpretability. 3.4. Recursive Re-Routing If the judged outcome is FAILURE, REDEREF executes a budgeted recursive step: (i) updateBeta(α i ā ,β i ā )with y = 0, (i) refine the query with the judgeās critique, and (i) re-route via Thompson sampling to the next most promising expert. The recursion terminates upon any of the following: 1. Success: the judge returns SUCCESS; 2. Depth limit: reaching a maximum recursion depth D; 3.Budget exhaustion: cumulative cost (tokens, time) ex- ceeding B; 4.Plateau: no judged improvement across recent itera- tions. This procedure is not full tree search (no rollout value esti- mation) but a lightweight, online mechanism that reliably 3 Training-Free Agentic AI for Multi-Agent LLM Systems recovers from local errors and discovers productive multi- agent chains with low overhead. The overall recursive pro- cedure of REDEREF, combining Bayesian delegation, self- reflection, query refinement, and memory-aware updating, is summarized in Algorithm 1. 3.5. Design Rationale Several design choices in Algorithm 1 merit justification. Why Thompson sampling over UCB orε-greedy? Thompson sampling naturally scales exploration to pos- terior uncertainty: when beliefs are diffuse (early rounds), it explores broadly; as posteriors concentrate, it exploits. UCB requires explicit tuning of the confidence parameter, and ε-greedy explores uniformly regardless of evidence, wasting budget on agents already known to be weak. Why selection over averaging? Averaging multiple agent outputs degrades quality when agents have heterogeneous competenceāa strong answer is diluted by weak ones. Se- lection with evidence preserves the best candidate while the bounded debate (two rounds) allows targeted refinement without the noise of full ensembling. Why cooldown? Without cooldown, a single false-positive verdict can cause the system to repeatedly select the same agent. The cooldownrforces exploration of alternatives after each selection, complementing the stochastic explo- ration of Thompson sampling with a deterministic diversity mechanism. Why binary feedback? Richer feedback (e.g., scalar scores) could accelerate learning but requires a well- calibrated scoring model. Binary success/failure is robust to judge miscalibrationāthe Beta-Bernoulli posterior is a conjugate update that remains valid even under moderate label noise (Theorem 3.1). 3.6. Memory-Aware Priors and Cold-Start Mitigation To reduce early-round inefficiency, we seed priors with similarity- and recency-weighted historical outcomes. α i ā α 0 + X m K(x d ,x m )y m w āt m ,(3) β i ā β 0 + X m K(x d ,x m ) (1ā y m )w āt m ,(4) wherex d = embed(q d ),Kis a task-similarity kernel (e.g., cosine over sentence embeddings), andw āt m = exp(āĪ»āt m )applies temporal decay. This initialization biases competence posteriors toward agents that recently succeeded on similar tasks while preserving adaptability under drift. Remark (Interpretability).The beta parameters(α i ,β i ), the rationales of the judgesĻ, and the selection history (agents chosen, verdicts, costs) constitute an auditable de- cision trail, which facilitates error analysis and responsible deployment. 3.7. Robustness Considerations The controller relies on binary feedback from a judge, which may be imperfect. To mitigate this, REDEREF incorpo- rates several robustness properties: (i) the Beta posterior is inherently resilient to occasional mislabeled feedback be- cause individual observations have diminishing influence as evidence accumulates; (i) the cooldown mechanism pre- vents the system from repeatedly exploiting a single agent based on a single lucky positive verdict; and (i) ensem- ble judges (majority voting over three independent judges) can further reduce sensitivity to individual judge errors at modest additional cost. 3.8. Regret Under Noisy Feedback We now quantify the cost of imperfect judging. Letε FP = Pr[E=SUCCESS | true fail] andε FN = Pr[E=FAILURE | true success]denote the judgeās false-positive and false- negative rates, and define the discrimination marginĪ“ = 1ā ε FP ā ε FN > 0. Theorem 3.1 (Regret under noisy judge feedback). Con- siderNagents with true competencesĪø 1 ,...,Īø N and a judge with class-conditional error rates(ε FP ,ε FN )satisfy- ingĪ“ = 1ā ε FP ā ε FN > 0. Then the Bayesian regret of Thompson sampling over T rounds satisfies R(T ) = 1 Ī“ e R(T ) = O ā NT logT Ī“ , where e R(T )is the regret of Thompson sampling on an equivalent noiseless problem with transformed competences Ģ Īø i = Ī“ Īø i + ε FP . Corollary 3.2. AsĪ“ ā 0(uninformative judge), regret diverges; asĪ“ ā 1(perfect judge), we recover the standard O( ā NT logT ) bound of Agrawal & Goyal (2013). The proof is given in Appendix A.5. Theorem 3.1 shows that judge noise inflates regret by exactly1/Ī“, providing a pre- cise budget for investing in judge quality versus accepting routing suboptimality. 3.9. Summary and Preview The framework provides one theoretical guarantee and three empirically testable properties. Theorem 3.1 bounds regret under noisy feedback asO( ā NT logT/Ī“), establishing that routing quality degrades gracefully with judge noise. The remaining propertiesāthat belief-guided routing im- 4 Training-Free Agentic AI for Multi-Agent LLM Systems proves efficiency over uninformed routing (H1), that posteri- ors concentrate on domain experts (H2), and that the routing policy adapts to agent degradation (H3)āare validated ex- perimentally in Sections 4ā5. 4. Experimental Design Because recursive retry already achieves high success on split-knowledge tasks, we treat task success as a constraint rather than the primary optimization objective. Our evalua- tion is therefore a controlled ablation: we isolate the effect of Bayesian belief-guided routing within an otherwise iden- tical recursive delegation loop, measuring whether informed agent selection improves token usage, agent calls, and time- to-first-success relative to uninformed (uniform random) selection. 4.1. Research Questions We organize evaluation around three dimensions (Figure 2): RQ1Composition efficiency (H1): At matched task success, does belief-guided routing reduce token usage, agent calls, and time-to-first-success compared to random re- cursive delegation? RQ2Specialization (H2): Do belief scores diverge over task sequences, with domain experts being preferentially se- lected for related tasks? RQ3Adaptability (H3): When a previously reliable agent is impaired mid-experiment, does the routing policy detect the degradation and redirect queries? 4.2. Tasks and Agent Population We constructed a benchmark of split-knowledge tasks via a three-stage pipeline (full details in Appendix): (i) domain- specific question generation for each agent (20ā22 questions each), (i) multi-agent task synthesis by sampling 4ā6 agents and composing questions that require non-redundant con- tributions from each, and (i) iterative sampling until the question pool was exhausted. By construction, each task requires contributions from multiple agents and cannot be solved by any single agent alone. The agent population comprises 6 specialist RAG agents (bi- ology, finance, law, medicine, electrical engineering, math- ematics) with retrieval over curated knowledge bases, and 10 generalist conversational agents (fitness, literature, tech- nology, geography, storytelling, politics, academics, career guidance, trivia, daily planning). All agents use Azure Ope- nAI endpoints with fixed random seeds for reproducibility. Agents are initialized with uniform priorsα 0 = β 0 = 1 unless memory-aware initialization is enabled. 4.3. Baseline Since split-knowledge tasks are unsolvable by any single agent, single-agent baselines are excluded by task design. The comparison instead isolates the routing mechanism: ā¢Random Delegation: The full recursive loop (judg- ing, re-routing, aggregation, budget limits) is retained identically, but agent selection at each step is uniformly random. This ensures that any observed difference is attributable to belief-guided routing rather than to recur- sion, judging, or aggregation. 4.4. Evaluation Metrics Performance (constraint): Task success rate (final score ā„ 85as judged by a calibrated LLM) and output quality, reported to confirm that both methods achieve compara- ble success. Efficiency (H1): Token usage, agent calls, and time-to-first-success, reported as ratios normalized to Random Delegation (lower is better). Specialization (H2): Belief score trajectories over task sequences and rounds-to- expert-selection for domain-specific tasks. Adaptability (H3): In an impairment test (50 normal followed by 50 degraded tasks for one agent), we track belief score decline, contribution frequency shift, and system output quality. Full metric definitions are provided in the Appendix. 5. Results and Analysis We summarize both effectiveness (success, quality) and effi- ciency/robustness (tokens, calls, latency, routing efficiency, and adaptation). Although recursion alone is surprisingly strong on our split-knowledge suite, REDEREF consis- tently shifts the efficiency frontier: at matched success it uses fewer tokens and agent calls, reaches the first success faster, and adapts under drift, whereas random delegation wastes capacity on unreliable agents. 5.1. Overall Performance and Efficiency Because recursive retry already saturates success on our split-knowledge tasks, we report success alongside ef- ficiency metrics (tokens, agent calls, and time-to-first- success). Random recursive delegation matches RED- EREF on success rate, but REDEREF substantially reduces wasted calls by prioritizing agents with higher historical marginal contribution. We report tokens, agent calls, and time-to-success normalized to Random Delegation (1.00Ć). Figure 3 complements the table by visualizing mean perfor- mance with confidence intervals, reinforcing that recursive retry saturates success, while REDEREF improves effi- ciency by reducing wasted calls and tokens. 5 Training-Free Agentic AI for Multi-Agent LLM Systems RQ1: Composition Efficiency RQ2: Specialization RQ3: Adaptability H1: Belief-guided routing reduces cost at matched success H2: Belief scores diverge, reflecting specialization H3: Routing adapts to impaired agents in real time ā Success Rate (constraint) ā Tokens ā Agent Calls ā Time-to-first-success ā Belief Score Evolution ā Rounds to Expert Selection ā Impairment Test (pre/post) ā Belief Score Decline ā Contribution Frequency ā Final Output Score Figure 2. Evaluation framework. Research questions, testable hypotheses, and associated metrics. Each dimension targets a distinct property of the routing mechanism. (a) Task success across delegation strategies (mean± 95% CI).(b) Output quality across delegation strategies (mean± 95% CI). Figure 3. Performance comparison across delegation strategies. (a) Task success rates (mean±95% CI) are saturated by recursive retry. (b) Output quality at convergence. REDEREF primarily improves efficiency (fewer calls/tokens) while maintaining comparable success. Error bars represent 95% confidence intervals. 5.2. Composition Dynamics and Efficiency Beyond aggregate performance, we examined how collabo- ration among multiple agents contributes to final outcomes. As shown in Figure 4a, average score improvements are highest when 3ā5 agents contribute meaningfully to the fi- nal output. This validates the intuition that composition efficiencyānot just redundancyādrives quality: a small coalition of diverse experts yields larger improvements than either a single agent or overly diffuse collaboration. 5.3. Ablation: Role of Belief Updates To isolate the impact of belief-driven delegation, we com- pared the full system to a variant in which agents were selected uniformly at random during recursive rerouting. As shown in Table 2, disabling belief updates leads to a 17.2% increase in the use of underperforming agents and an 8.2% increase in exploratory attempts before reaching a successful outcome. Both differences are statistically sig- nificant under paired bootstrap tests (p < 0.01). While the number of useful contributors remains similar, the random policy wastes capacity on unreliable agents, underscoring Table 1. Efficiency comparison at matched task success. Tokens, Agent Calls, and Time-to-Success are reported as ratios normalized to Random Delegation; lower is better. MethodSuccess (%)Tokens (ā)Agent Calls (ā)Time-to-Success (ā) Random Delegation96.461.00Ć1.00Ć1.00Ć REDEREF (Full)96.650.72Ć0.83Ć0.81Ć Table 2. Routing behavior with and without belief updates (mean ± 95% CI). MethodBad Agent UsesGood Agent UsesTotal Attempted Random Delegation6.62± 0.44.92± 0.211.54± 0.5 REDEREF (Full)5.65± 0.35.01± 0.210.67± 0.4 that experience-driven learning enhances both efficiency and robustness. 5.4. Specialization We next examined whether agents developed stable spe- cializations over time. In a sequence of 55 electrical- engineering tasks, the median belief score for the domain ex- pert rose from 0.50 (±0.02) to 0.84 (±0.03). Concurrently, 6 Training-Free Agentic AI for Multi-Agent LLM Systems (a) Average quality improvement vs. number of contributing agents. Collabora- tion among 3ā5 strong contributors yields the largest quality improvements. (b) Average rounds until Electrical Engineering ex- pert was selected across task halves. Figure 4. Collaboration dynamics and specialization. (a) Average quality gain versus number of contributing agents, showing peak composition efficiency at 3ā5 agents. (b) Decline in rounds required to select the Electrical Engineering expert across task sequence, demonstrating specialization via posterior concentration. Table 3. Adaptability under impairment: Biology agent perfor- mance before and after enforced degradation (mean± 95% CI). MetricNormalImpaired Average Belief Score0.35± 0.020.23± 0.03 Agent Contributions12± 1.10 Final Output Score84.52± 0.781.80± 0.9 the average number of rounds required before this expert was selected declined from 8.11 (±0.4) to 6.86 (±0.3), as shown in Figure 4b. This trajectory demonstrates that RED- EREF not only improves aggregate performance but also learns to preferentially route domain-specific queries to the most competent agentsāconsistent with specialization via posterior concentration (supporting H2). 5.5. Adaptability to Agent Impairment To evaluate adaptability (H3), we conducted an impairment test in which theBiologyRAGAgentwas replaced with systematically poor outputs after the first 50 tasks. As shown in Table 3, the agentās belief score decreased by almost 50%, and its contributions were eliminated completely in subse- quent tasks. While the overall output quality decreased mod- estly (84.52±0.7 to 81.80±0.9), the system dynamically reallocated queries to other competent agents, preventing catastrophic degradation. This rapid adjustment is also illus- trated in Figure 5, which shows diverging belief trajectories for the impaired and healthy agents. Figure 5. Adaptability under agent impairment. Belief score tra- jectories for the Biology agent under normal versus systematically impaired conditions. The system rapidly detects degradation and down-weights the compromised agent, demonstrating real-time adaptability. 5.6. Qualitative Dynamics Qualitative inspection further illustrates REDEREFās re- cursive dynamics. In one representative task, the system initially delegated to an electrical-engineering agent, which produced a technically correct but incomplete design. After a failure judgment, REDEREF re-delegated to a narrative- oriented agent, which supplied the missing community- education perspective. The final aggregated response inte- grated both technical and social dimensions and was judged successful. Such trajectories exemplify how recursive re- routing enables the system to synthesize complementary expertise and recover from early missteps. Summary.In summary, belief-guided routing reduces to- ken usage, agent calls, and time-to-success at matched suc- 7 Training-Free Agentic AI for Multi-Agent LLM Systems cess rates (H1), belief scores concentrate on domain experts over task sequences (H2), and the routing policy adapts when an agent is impaired mid-experiment (H3). All three hypotheses from Section 4 are supported. 6. Discussion and Conclusion We introduced REDEREF, a lightweight, training-free con- troller for multi-agent LLM systems that addresses three persistent challenges in multi-agent collaboration: dynamic task routing, long-horizon credit assignment, and cold-start inefficiency. By combining Thompson-sampling delegation, reflection-driven updates, and memory-aware priors, RED- EREF maintains saturated task success while improving routing efficiency and robustness with minimal overhead. Key insights. Our findings support a growing body of evidence that lightweight, interpretable mechanisms can rival or surpass resource-intensive pipelines. The proba- bilistic control formulation resonates with models of agent trust (Wu et al., 2021) and bandit methods for online decision-making (Chapelle & Li, 2011), while avoiding the instability and sample inefficiency of deep RL (Mnih et al., 2015). The recursive loop mirrors ideas from search- based reasoning such as Monte Carlo Tree Search (Browne et al., 2012), yet operates at a fraction of the computational cost. In ablations, removing belief-guided routing increased poor-agent usage by 17.2% and wasted attempts, underscor- ing the critical importance of online feedback for efficient coordination. Limitations.REDEREF depends critically on judge re- liability; biases in machine adjudication are well docu- mented (Karpinska et al., 2021) and can distort competency updates, potentially entrenching suboptimal routing deci- sions. Sequential recursion can add latency in long tasks, limiting applicability in real-time scenarios. Early cold- start behavior resembles random delegation before sufficient evidence accumulates to differentiate agent competencies. These limitations highlight the need for robust judge calibra- tion, potential parallelization of candidate generation, and more informative prior initialization strategies. Broader implications. The transparency of REDEREF is advantageous for responsible AI deployment: Beta pos- teriors, judge verdicts, and natural language rationales cre- ate an auditable decision trail (Doshi-Velez & Kim, 2017), contrasting sharply with opaque RL policies or heavily fine-tuned black-box controllers. However, adaptive down- weighting based on early evidence could prematurely ex- clude competent agents, particularly in scenarios with tem- porary performance fluctuations. Periodic recalibration and ensemble judge mechanisms are therefore important for reliable deployment in sensitive domains. Future directions. Several extensions warrant investiga- tion. Hybridizing Bayesian delegation with model-based reinforcement learning could combine fast online adaptation with long-term strategic planning (Silver et al., 2017). Ex- panding beyond binary success/failure feedback into richer error taxonomies (e.g., reasoning errors, factual inaccura- cies, incomplete coverage) would enable more fine-grained credit assignment and targeted agent improvement. Paral- lel candidate generation could significantly reduce latency while maintaining bounded computational budgets. Finally, programmatic verifiers and retrieval-grounded evaluation models (Min et al., 2023) offer promising directions for im- proving judge reliability and reducing calibration overhead. Conclusion. Robust collaboration in LLM collectives does not require complex black-box architectures or ex- tensive training. Simple probabilistic mechanismsābelief- guided delegation, calibrated reflection, and memory-aware priorsācan transform collections of independent agents into cohesive, adaptive systems. 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STAGE 1: SINGLE-AGENT QUESTION GENERATION We first generated domain-specific questions tailored to two classes of agents: ā¢RAG Agents: Retrieval-augmented models grounded in curated domain datasets (e.g., biology, finance, medicine) (Hugging Face, 2025). ā¢Conversational Agents: Prompt-based agents cover- ing domains such as career guidance, fitness, or litera- ture. Each agent was tasked with producing 20ā22 realistic ques- tions, paired with a Model Context Protocol (MCP) captur- ing intent, tools, and plausible follow-ups. All outputs were archived in structured JSON format. A.1.2. STAGE 2: MULTI-AGENT TASK SYNTHESIS Single-agent questions were combined into multi-agent tasks by sampling 4ā6 diverse agents and synthesizing 15 composite tasks per batch. Each task was required to: ā¢Necessitate distinct, non-redundant contributions from each agent, ā¢Require multi-layered reasoning (planning, analysis, execution), ⢠Include a merged MCP integrating the intents, tools, and follow-ups of all contributing agents. Examples include generating healthcare policy reports using medical, political, and geographic agents, or constructing recovery plans with biology, fitness, finance, and scheduling agents. A.1.3. STAGE 3: ITERATIVE SAMPLING This process was repeated until the pool of questions was exhausted, yielding a benchmark suite explicitly designed to enforce distributed reasoning. Each task was unsolvable by any single agent, thereby ensuring collaborative evaluation. A.2. Extended Metric Definitions This section provides full definitions of the evaluation met- rics summarized in Section 4. A.2.1. PERFORMANCE ā¢Task Success Rate: Percentage of tasks achieving a final answer scoreā„ 85 as judged by an LLM. ā¢Agents Attempted: Average number of agents in- voked before reaching a solution. A.2.2. SPECIALIZATION (H2) ā¢Belief Score Evolution: Temporal trajectories ofb i for domain experts (e.g., Math agent). ā¢Rounds to Expert Selection: Average delegation steps before the correct expert is chosen for domain-specific tasks, expected to decline as belief updates accumulate. A.2.3. ADAPTABILITY (H3) ā¢Agent Impairment Test: Across 100 tasks, one agent (e.g., Biology) operates normally for the first 50, then is forced to fail for the next 50. ā¢Belief Score Decline: Comparison of belief trajecto- ries pre- and post-impairment. ā¢Contribution Frequency: Task participation counts across both phases. ⢠System Output Score: Average final answer score across both segments, reflecting resilience to impaired agents. A.2.4. COMPOSITION EFFICIENCY (H1) ā¢Time-to-first-success: Number of delegation rounds required to produce the first judged-successful candi- date. ⢠Marginal contribution efficiency: Improvement in output score per token consumed by each contributing agent. A.3. Implementation Details A.3.1. FRAMEWORK ARCHITECTURE The REDEREF framework is implemented as a modular pipeline consisting of six core components: WorkflowManager,BayesianDelegator, SelfReflectionStep,InfoMergeStep, MemoryUpdateStep,andRecursiveRouting. TheWorkflowManagerserves as the main orchestrator, coordinating agent delegation, reflection, memory updates, and recursive re-routing according to Algorithm 1. 10 Training-Free Agentic AI for Multi-Agent LLM Systems Core Classes and Data Structures. The centralTask class maintains task state including query text, agent out- puts, reflection scores, memory updates, and completion status. Agent performance is tracked through belief param- eters(α i ,β i ), cooldown counters, and historical success rates. The framework supports both Bayesian delegation via Thompson sampling and traditional LLM-based ranking through a configurable usebayesian parameter. A.3.2. BAYESIAN DELEGATION IMPLEMENTATION Thompsonsamplingisimplementedinthe BayesianDelegatorclasswiththefollowing key features: ⢠Agent Selection: For each agenti, sample Ė Īø i ā¼ Beta(α i ,β i )and selecti ā = arg max i Ė Īø i (subject to cooldown constraints). ⢠Binary Updates: After judging, updateα i ā ā α i ā + y andβ i ā ā β i ā + (1ā y)wherey ā 0, 1indicates success/failure. ā¢Cooldown Mechanism: Agents are temporarily ex- cluded forrrounds after selection to encourage explo- ration. If all agents are cooling, the framework forces exploration by selecting the agent with the smallest re- maining cooldown. ā¢Belief Persistence: Agent beliefs are stored in JSON format and loaded across sessions to maintain long-term memory. A.3.3. MEMORY-AWARE PRIOR INITIALIZATION Historical performance data is used to initialize belief priors via similarity-weighted aggregation: Lets m = K(embed(q), embed(q m ))Ā· exp(āĪ»āt m ). Then: α i ā α 0 + P māM s m Ā· y m ,(5) β i ā β 0 + P māM s m Ā· (1ā y m ),(6) whereK(Ā·,Ā·)is cosine similarity over sentence embeddings, āt m is task recency, andĪ» = 0.1controls temporal decay. This initialization reduces cold-start inefficiency by biasing selection toward agents with historically strong performance on similar tasks. A.3.4. MULTI-LAYERED JUDGE SYSTEM TheSelfReflectionStepimplements a four-stage evaluation pipeline: 1. Agent Output Scoring: Individual agent responses are scored on a 0-100 scale using task-specific rubrics. 2.Binary Success Evaluation: A calibrated LLM judge determines whether the merged output satisfies task re- quirements, yielding E āSUCCESS, FAILURE. 3.Completeness Assessment:The judge evaluates whether additional agent input would improve the re- sponse quality. 4.Agent Refinement: Underperforming agent outputs are iteratively improved based on judge critiques. Judge calibration is performed on a held-out validation set of 200 labeled examples to estimate false positive/negative rates and set decision thresholds. A.3.5. AGENT ZOO SPECIFICATION The experimental agent population consists of two classes: ⢠RAGAgents:Domain-specificagents (ExpertAgent)withretrievalaugmentation over curated knowledge bases.Domains include mathematics, law, finance, biology, medicine, and electrical engineering. Each agent loads domain-specific datasets and uses specialized prompt templates with retrieval-grounded context. ā¢ConversationalAgents:LLM-basedagents (ConversationalAgent)withoutretrieval, covering fitness, literature, technology, geography, storytelling, politics, academics, career guidance, trivia, and daily planning. Agent configurations are specified in YAML format with domain-specific constraints and prompt templates. All agents are initialized with uniform priorsα 0 = β 0 = 1 unless memory-aware initialization is enabled. A.3.6. INFORMATION MERGING AND TRUST WEIGHTING TheInfoMergeStepaggregates agent responses using trust-weighted selection: 1.Compute trust scorest i = α i /(α i + β i )for each con- tributing agent. 2.Filter responses from agents marked as ābadā (belief score below threshold). 3. Merge remaining responses using LLM-based synthesis weighted by trust scores. 4.Validate merged output through evidence-grounding and consistency checks. 11 Training-Free Agentic AI for Multi-Agent LLM Systems A.3.7. EXPERIMENTAL INFRASTRUCTURE Theevaluationframework (runbeliefexperiment.py) supports: ā¢Configurable Agent Selection: Systematic sampling from the agent zoo with controllable population size. ā¢Question Processing Pipeline: Batch processing with configurable delays and timeout handling. ā¢Comprehensive Logging: Results are logged to struc- tured JSON files including initial outputs, recursive del- egation traces, final merged responses, and detailed per- formance metrics. ā¢Statistical Validation: Built-in A/B testing, bootstrap confidence intervals, and performance benchmarking capabilities. A.3.8. EVALUATION METRICS IMPLEMENTATION Quality assessment employs a multi-faceted scoring system: ā¢Output Quality: 0-100 scale scoring of initial vs. merged outputs using task-specific rubrics. ā¢Quality Gains: Absolute improvement (merged - initial) and relative improvement ((merged - initial) / initial). ā¢Agent Contribution Tracking: Classification of agents as ācontributingā (positive impact) vs. ābadā (negative impact) based on comparative evaluation. ā¢Routing Statistics: Delegation depth, agent selection frequency, and belief evolution trajectories. A.3.9. REPRODUCIBILITY AND CONFIGURATION All experiments are reproducible through: ā¢Deterministic Sampling: Fixed random seeds for Thompson sampling and LLM generation. ⢠Configuration Management: YAML-based agent spec- ifications and experimental parameters. ā¢Version Control: Git-tracked experimental runs with commit hashes logged in results. ā¢Environment Specification: Docker containers with fixed dependency versions and Azure OpenAI API con- figurations. A.3.10. COMPUTATIONAL REQUIREMENTS Typical experimental runs require: ā¢Hardware: 16GB RAM, 4-core CPU for coordination logic; GPU optional for local LLM inference. ā¢API Costs: $0.50-2.00 per task depending on recursion depth and agent complexity. ā¢Runtime: 2-5 minutes per task with Azure OpenAI; 30-60 seconds with local models. ā¢Storage: 10-50MB per 100 tasks for complete logs and belief persistence. A.4. LLM-in-the-Loop Evaluation Our pipeline uses LLMs for task generation, agent execu- tion, and judging, which raises a potential circularity con- cern. We mitigate this in three ways: (i) programmatic metrics (EM, F1, unit-test pass rates) short-circuit the judge for unambiguous cases, grounding a substantial fraction of verdicts in non-LLM signals; (i) the judge is calibrated on 200 human-labeled examples with measured FP/FN rates, so its error profile is quantified rather than assumed reliable; and (i) agent outputs and judge verdicts are produced by independent LLM calls with no shared state, preventing self- reinforcing feedback loops. The routing controller itself is purely probabilistic (Beta-Bernoulli updates) and contains no learned LLM parameters. While fully human-grounded evaluation remains the gold standard, these safeguards en- sure that the LLM-based components are calibrated, par- tially redundant with programmatic checks, and structurally decoupled. A.5. Proof of Theorem 3.1: Regret Under Noisy Judge Feedback Setup. There areNarms (agents) with true Bernoulli success probabilitiesĪø 1 ,...,Īø N . The judge observes each outcome through a binary symmetricālike channel with false-positive rateε FP and false-negative rateε FN , so the observed success probability of arm i is Ģ Īø i = (1ā ε FN )Īø i + ε FP (1ā Īø i ) = Ī“ Īø i + ε FP , where Ī“ = 1ā ε FP ā ε FN > 0. Lemma A.1 (Order preservation). SinceĪ“ > 0, the map Īø i 7ā Ģ Īø i is strictly increasing. HenceĪø i ā > Īø j if and only if Ģ Īø i ā > Ģ Īø j ; the optimal arm is unchanged. Lemma A.2 (Gap contraction). For any suboptimal armj, the observed gap satisfies Ģ ā j = Ģ Īø i ā ā Ģ Īø j = Ī“ ā j , where ā j = Īø i ā ā Īø j . 12 Training-Free Agentic AI for Multi-Agent LLM Systems Main argument.The controller never sees true outcomes; it runs Thompson sampling on the observed Bernoulli prob- lem Ģ Īø i N i=1 . By Lemma A.1, the optimal observed arm coincides with the truly optimal armi ā . Applying the Bayesian regret bound of Agrawal & Goyal (2013) (Theo- rem 2 therein) to the observed problem yields e R(T ) = X jĢø=i ā Ģ ā j E[n j (T )] = O p NT logT . The true regret decomposes as R(T ) = T X t=1 Īø i ā ā Īø I t = X jĢø=i ā ā j E[n j (T )] = X jĢø=i ā Ģ ā j Ī“ E[n j (T )] = 1 Ī“ e R(T ) = O ā NT logT Ī“ , (7) where we used Lemma A.2 in the penultimate step. This completes the proof. Algorithm 1 REDEREF: Recursive Delegation and Reflec- tion Require:Queryq, agentsA 1 ..A N with(α i ,β i ), memory M, judge J , max depth D, budget B, cooldown r 1: xā embed(q) 2: initialize (α i ,β i ) via memory-aware priors fromM 3: cool[i]ā 0 for all i; spentā 0 4: C āā set of all candidates with evidence 5: (best, bestScore)ā (ā ,āā) 6: for d = 1 to D do 7:if spentā„ B then break 8:end if 9: Sampling: for eachi, draw Ė Īø i ā¼ Beta(α i ,β i )if cool[i] = 0 else set Ė Īø i āāā 10: ifmax i Ė Īø i =āāthenall cooling; force one step of exploration 11:setcool[j] ā 0forj = arg max i cool[i] or the smallest cooldown 12:continue 13:end if 14: i ā ā arg max i Ė Īø i tie-break by largerα i /(α i + β i ) 15:(cand, usage)ā A i ā (q) 16:spent += usage 17:if spent > B then break 18:end if 19:score prog ā programmatic metrics(q, cand) 20:if score prog is unambiguous positive then 21:E ā SUCCESS; Ļā āprogrammatic passā 22:else 23:(E,Ļ, score judge )ā J (q, cand, score prog ) 24:end if 25: y ā I[E = SUCCESS] 26: α i ā += y; β i ā += (1ā y) 27: MāMāŖ(x,i ā ,y,Ļ, now()) 28: C āCāŖ(cand, score prog , score judge ,i ā ) 29:candScoreā combine scores(score prog , score judge ) 30:if candScore > bestScore then 31:(best, bestScore)ā (cand, candScore) 32:end if 33:if y = 1 then 34: returnaggregateselect(C,μ i = α i /(α i + β i ))selection with evidence 35:end if 36:cool[i ā ] ā r ; for allj:cool[j] ā max(0, cool[j]ā 1) 37: q ā refine(q, cand,Ļ) 38: ifplateau(C,k)then breakno score improve- ment over last k attempts 39:end if 40: end for 41: ifC Ģø=ā then 42:returnaggregateselect(C,μ i ) best-so-far with evidence checks 43: else 44:return FAILUREno candidate produced 45: end if 13