COMPASS: Critique-guided Optimization of MetaPolicies for Agentic Systems with Reinforcement Learning

Krishna Sayana, Ketan Kumar Todi, Ambarish Jash, Sukhdeep Sodhi


Abstract
As large language models are increasingly deployed as autonomous agents, optimizing their behavior in agentic reasoning and tool-use environments remains challenging due to the stochasticity of environment trajectories and associated high reward latencies. Existing automated prompt optimization (APO) paradigms struggle in these regimes: discrete evolutionary methods (e.g., GEPA, ACE) lack parametric memory, while instance-level reinforcement learning (RL) approaches suffer from severe gradient variance and reward collapse on small, human-curated datasets. To address these limitations, we introduce COMPASS (Critique-guided Optimization of MetaPolicies for Agentic SystemS), a sample-efficient dual-agent framework that shifts optimization toward task-level metapolicies and demonstrates that an RL-based prompter policy can be effectively trained on such tasks. To overcome sparse feedback, COMPASS introduces a Critique Experience Buffer that couples scalar rewards with dense textual critiques. This mechanism allows an active “Prompter” policy to internalize corrective linguistic patterns and amortize experiential self-reflection directly into its weights. Empirical evaluations demonstrate that COMPASS stabilizes training and yields up to 2.4× faster convergence. On complex reasoning (BBEH) and tool-use (𝜏-bench) benchmarks, our framework improves success rates from 55% to 90% and 74% to 91%, respectively, while naturally discovering specialized algorithmic strategies.
Anthology ID:
2026.realm-1.77
Volume:
Proceedings of the Second Workshop for REsearch on Agent Language Models (REALM 2026)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Ehsan Kamalloo, Nicolas Gontier, Nikolai Rozanov, Maryam Hashemzadeh, Akhil Arora
Venues:
REALM | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
1118–1143
Language:
URL:
https://aclanthology.org/2026.realm-1.77/
DOI:
Bibkey:
Cite (ACL):
Krishna Sayana, Ketan Kumar Todi, Ambarish Jash, and Sukhdeep Sodhi. 2026. COMPASS: Critique-guided Optimization of MetaPolicies for Agentic Systems with Reinforcement Learning. In Proceedings of the Second Workshop for REsearch on Agent Language Models (REALM 2026), pages 1118–1143, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
COMPASS: Critique-guided Optimization of MetaPolicies for Agentic Systems with Reinforcement Learning (Sayana et al., REALM 2026)
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PDF:
https://aclanthology.org/2026.realm-1.77.pdf