AgentRM: Enhancing Agent Generalization with Reward Modeling

Fuente: arXiv
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Main Authors: Xia, Yu, Fan, Jingru, Chen, Weize, Yan, Siyu, Cong, Xin, Zhang, Zhong, Lu, Yaxi, Lin, Yankai, Liu, Zhiyuan, Sun, Maosong
Format: Preprint
Published: 2025
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_version_ 1866917935969206272
author Xia, Yu
Fan, Jingru
Chen, Weize
Yan, Siyu
Cong, Xin
Zhang, Zhong
Lu, Yaxi
Lin, Yankai
Liu, Zhiyuan
Sun, Maosong
author_facet Xia, Yu
Fan, Jingru
Chen, Weize
Yan, Siyu
Cong, Xin
Zhang, Zhong
Lu, Yaxi
Lin, Yankai
Liu, Zhiyuan
Sun, Maosong
contents Existing LLM-based agents have achieved strong performance on held-in tasks, but their generalizability to unseen tasks remains poor. Hence, some recent work focus on fine-tuning the policy model with more diverse tasks to improve the generalizability. In this work, we find that finetuning a reward model to guide the policy model is more robust than directly finetuning the policy model. Based on this finding, we propose AgentRM, a generalizable reward model, to guide the policy model for effective test-time search. We comprehensively investigate three approaches to construct the reward model, including explicit reward modeling, implicit reward modeling and LLM-as-a-judge. We then use AgentRM to guide the answer generation with Best-of-N sampling and step-level beam search. On four types of nine agent tasks, AgentRM enhances the base policy model by $8.8$ points on average, surpassing the top general agent by $4.0$. Moreover, it demonstrates weak-to-strong generalization, yielding greater improvement of $12.6$ on LLaMA-3-70B policy model. As for the specializability, AgentRM can also boost a finetuned policy model and outperform the top specialized agent by $11.4$ on three held-in tasks. Further analysis verifies its effectiveness in test-time scaling. Codes will be released to facilitate the research in this area.
format Preprint
id arxiv_https___arxiv_org_abs_2502_18407
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle AgentRM: Enhancing Agent Generalization with Reward Modeling
Xia, Yu
Fan, Jingru
Chen, Weize
Yan, Siyu
Cong, Xin
Zhang, Zhong
Lu, Yaxi
Lin, Yankai
Liu, Zhiyuan
Sun, Maosong
Computation and Language
Artificial Intelligence
Machine Learning
Existing LLM-based agents have achieved strong performance on held-in tasks, but their generalizability to unseen tasks remains poor. Hence, some recent work focus on fine-tuning the policy model with more diverse tasks to improve the generalizability. In this work, we find that finetuning a reward model to guide the policy model is more robust than directly finetuning the policy model. Based on this finding, we propose AgentRM, a generalizable reward model, to guide the policy model for effective test-time search. We comprehensively investigate three approaches to construct the reward model, including explicit reward modeling, implicit reward modeling and LLM-as-a-judge. We then use AgentRM to guide the answer generation with Best-of-N sampling and step-level beam search. On four types of nine agent tasks, AgentRM enhances the base policy model by $8.8$ points on average, surpassing the top general agent by $4.0$. Moreover, it demonstrates weak-to-strong generalization, yielding greater improvement of $12.6$ on LLaMA-3-70B policy model. As for the specializability, AgentRM can also boost a finetuned policy model and outperform the top specialized agent by $11.4$ on three held-in tasks. Further analysis verifies its effectiveness in test-time scaling. Codes will be released to facilitate the research in this area.
title AgentRM: Enhancing Agent Generalization with Reward Modeling
topic Computation and Language
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2502.18407