J-ToRL: Tool-Integrated LLM-as-a-Judge via Reinforcement Learning

Bryan Wilie, Tiezheng YU, Gerry Windiarto Mohamad Dunda, Jierun Chen, Chaofan Tao, Yan Xu, Junxian He, Pascale Fung


Abstract
LLM-as-a-Judge frameworks offer scalable alternatives to human evaluation but inherit the limitations of text-only reasoning, particularly in tasks requiring precise computations. We introduce J-ToRL, a framework that trains LLM judges to leverage computational tools via code generation through end-to-end reinforcement learning (RL). Unlike prior approaches relying on inference-time integration, J-ToRL internalizes tool-use strategies as part of its policy, enabling exploration of diverse reasoning pathways. We identify a key challenge in applying RL with verifiable rewards to judgment: the coarse reward signals inherent in multiple-choice verdicts can incentivize shortcut learning. J-ToRL mitigates this via an auxiliary verifiable reward mechanism based on reference-answers, that enforces stricter criteria beyond simple verdict accuracy alone. With a sophisticated pairwise comparison dataset across five domains, J-ToRL-trained LLMs improve the base models, outperform prior judges, and close the gap to frontier LLMs. Further, J-ToRL-trained models exhibit beneficial cognitive behaviors such as self-error-recovery and self-refinement of tool use strategies.
Anthology ID:
2026.aacl-long.46
Volume:
Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venues:
AACL | IJCNLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
952–965
Language:
URL:
https://aclanthology.org/2026.aacl-long.46/
DOI:
Bibkey:
Cite (ACL):
Bryan Wilie, Tiezheng YU, Gerry Windiarto Mohamad Dunda, Jierun Chen, Chaofan Tao, Yan Xu, Junxian He, and Pascale Fung. 2026. J-ToRL: Tool-Integrated LLM-as-a-Judge via Reinforcement Learning. In Proceedings of the 15th International Joint Conference on Natural Language Processing and the 5th Conference of the Asia-Pacific Chapter of the Association for Computational Linguistics (Volume 1: Long Papers), pages 952–965, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
J-ToRL: Tool-Integrated LLM-as-a-Judge via Reinforcement Learning (Wilie et al., AACL-IJCNLP 2026)
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https://aclanthology.org/2026.aacl-long.46.pdf