ResearchResearch paperAgents & Tool Use2 sources · Oct 19, 2026

Which Agent's Skill Should Change? Group-Relative Credit Assignment for Evolving Multi-Agent Teams

We present GRSE, Group-Relative Skill Evolution, which assigns behavioral credit by comparison: inspired by GRPO, it executes each question several times under the same skill libraries and contrasts the executions to credit agent--skill pairs, with structured diagnosis of failures.

Key points

  • Cooperative language-model agents can improve without weight updates by revising reusable skills, but only if a shared team reward is traced to the responsible agent and skill.
  • Existing methods credit the skills present in each trajectory, yet presence is not responsibility: a harmful skill active in successful runs still earns positive credit.
  • On HotpotQA and LoCoMo with two open-weight actors, GRSE outperforms MASkills, the closest prior method, on HotpotQA and every LoCoMo category except open-domain, with the largest gains on multi-hop questions (+6.7 and +3.2 F1).
  • GRSE is robust to corrupted libraries: starting from planted harmful skills, it credits every planted skill with the correct sign and recovers the score of a clean library (+6.3 points), whereas MASkills misattributes two and falls below its starting point.

Sources (2)

Extractive summary: sentences quoted from the sources.

Before this

  1. Oct 18, 2026EG-GRPO: Evidence-Guided Step-level Credit Assignment for Deep Search Agents
  2. Oct 18, 2026Indistinguishable Agents: Training Agent Privacy as Twin-World Indistinguishability
  3. Oct 18, 2026Trackable Skill Library Lifecycle Management for Agentic Reinforcement Learning
  4. Oct 18, 2026Over-Defense in Coding Agents Begins at Silent Forks
  5. Oct 17, 2026MELD: Recursive Self-Improvement via Hierarchical Coordination for Multi-Agent Scientific Discovery
  6. Oct 16, 2026Not Every User Says It All: Training Tool-Using Agents Beyond Ideal Simulated Users

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