SkillRubricsRL: Evolving Skill-Grounded Agents with Rubric-Guided Reinforcement Learning

Zihe Huang, Jianfei Pan, YiFan Zhang, Tao Chen, Jinghao Lin, Kai Ruan, Xiucheng Xu, Jian Yao, Yijun He, Haihua Yang


Abstract
Long-horizon LLM agents increasingly rely on retrieved procedural skills as external memory. However, existing skill-augmented RL frameworks typically supervise a bundle of retrieved skills only with trajectory-level outcome rewards, leaving two key questions unanswered: whether each skill was executed and whether it helped task completion. We formulate this as a per-skill credit assignment problem. To address it, we propose SkillRubricsRL, which pairs each skill with an applicability-aware trajectory-level rubric and derives two complementary signals: a fulfillment signal for training correct skill execution and a counterfactual utility signal for retrieval and skill-bank evolution. Across ALFWorld and WebShop, SkillRubricsR achieves 97.7% ALFWorld success, 84.4% WebShop success, and a WebShop score of 92.7, improving over the strongest prior multi-skill baseline by 2.8, 2.1, and 1.6 percentage points, respectively, while increasing skill execution rate by over 50 percentage points. Code is available at https://github.com/gminiheimdallr-a11y/SkillRubricsRL.
Anthology ID:
2026.findings-emnlp.471
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
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SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
9870–9885
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URL:
https://aclanthology.org/2026.findings-emnlp.471/
DOI:
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Cite (ACL):
Zihe Huang, Jianfei Pan, YiFan Zhang, Tao Chen, Jinghao Lin, Kai Ruan, Xiucheng Xu, Jian Yao, Yijun He, and Haihua Yang. 2026. SkillRubricsRL: Evolving Skill-Grounded Agents with Rubric-Guided Reinforcement Learning. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 9870–9885, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
SkillRubricsRL: Evolving Skill-Grounded Agents with Rubric-Guided Reinforcement Learning (Huang et al., Findings 2026)
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https://aclanthology.org/2026.findings-emnlp.471.pdf