SCRIBE: Learning Reusable Skill Rubrics for Process Reward Models

Yuxuan Jiang, Francis Ferraro


Abstract
Training reliable tool-augmented agents remains challenging due to the difficulty of credit assignment in multi-step reasoning. Process Reward Models (PRMs) provide a natural solution by assigning rewards to intermediate reasoning steps or trajectories, but standard LLM-based judges often produce inconsistent signals due to underspecified evaluation criteria. Recent rubric-based reward methods improve reward quality by making scoring criteria explicit, yet they typically rely on reference answers and construct instance-level rubrics that are difficult to reuse across examples. In this work, we propose SCRIBE (Skill-Conditioned Reward with Intermediate Behavioral Evaluation), a reinforcement learning framework for reusable subgoal-level rubric rewards. SCRIBE decomposes reasoning trajectories into intermediate subgoals, clusters semantically similar reasoning behaviors into reusable Skill Prototypes, and grounds reward evaluation in prototype-level scoring criteria. This transforms reward modeling from instance-specific open-ended evaluation into reusable process-level verification. Empirical results show that SCRIBE consistently outperforms strong RL and rubric-based reward baselines across mathematical reasoning and tool-use benchmarks; notably, it improves the AIME25 score of a Qwen3-4B model from 43.3% to 63.3%. Further analysis shows that SCRIBE reduces dependence on reference answers and provides more stable, cross-instance consistent reward judgments, offering a scalable approach to reliable process reward modeling for tool-augmented agents.
Anthology ID:
2026.emnlp-main.797
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
18512–18526
Language:
URL:
https://aclanthology.org/2026.emnlp-main.797/
DOI:
Bibkey:
Cite (ACL):
Yuxuan Jiang and Francis Ferraro. 2026. SCRIBE: Learning Reusable Skill Rubrics for Process Reward Models. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 18512–18526, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
SCRIBE: Learning Reusable Skill Rubrics for Process Reward Models (Jiang & Ferraro, EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.797.pdf