ToolPRMBench: Evaluating and Advancing Process Reward Models for Tool-using Agents

Fuente: arXiv
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Main Authors: Li, Dawei, Yao, Yuguang, Tan, Zhen, Liu, Huan, Guo, Ruocheng
Format: Preprint
Published: 2026
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author Li, Dawei
Yao, Yuguang
Tan, Zhen
Liu, Huan
Guo, Ruocheng
author_facet Li, Dawei
Yao, Yuguang
Tan, Zhen
Liu, Huan
Guo, Ruocheng
contents Reward-guided search methods have demonstrated strong potential in enhancing tool-using agents by effectively guiding sampling and exploration over complex action spaces. As a core design, those search methods utilize process reward models (PRMs) to provide step-level rewards, enabling more fine-grained monitoring. However, there is a lack of systematic and reliable evaluation benchmarks for PRMs in tool-using settings. In this paper, we introduce ToolPRMBench, a large-scale benchmark specifically designed to evaluate PRMs for tool-using agents. ToolPRMBench is built on top of several representative tool-using benchmarks and converts agent trajectories into step-level test cases. Each case contains the interaction history, a correct action, a plausible but incorrect alternative, and relevant tool metadata. We respectively utilize offline sampling to isolate local single-step errors and online sampling to capture realistic multi-step failures from full agent rollouts. A multi-LLM verification pipeline is proposed to reduce label noise and ensure data quality. We conduct extensive experiments across large language models, general PRMs, and tool-specialized PRMs on ToolPRMBench. The results reveal clear differences in PRM effectiveness and highlight the potential of specialized PRMs for tool-using. Code and data will be released at https://github.com/David-Li0406/ToolPRMBench.
format Preprint
id arxiv_https___arxiv_org_abs_2601_12294
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle ToolPRMBench: Evaluating and Advancing Process Reward Models for Tool-using Agents
Li, Dawei
Yao, Yuguang
Tan, Zhen
Liu, Huan
Guo, Ruocheng
Artificial Intelligence
Software Engineering
Reward-guided search methods have demonstrated strong potential in enhancing tool-using agents by effectively guiding sampling and exploration over complex action spaces. As a core design, those search methods utilize process reward models (PRMs) to provide step-level rewards, enabling more fine-grained monitoring. However, there is a lack of systematic and reliable evaluation benchmarks for PRMs in tool-using settings. In this paper, we introduce ToolPRMBench, a large-scale benchmark specifically designed to evaluate PRMs for tool-using agents. ToolPRMBench is built on top of several representative tool-using benchmarks and converts agent trajectories into step-level test cases. Each case contains the interaction history, a correct action, a plausible but incorrect alternative, and relevant tool metadata. We respectively utilize offline sampling to isolate local single-step errors and online sampling to capture realistic multi-step failures from full agent rollouts. A multi-LLM verification pipeline is proposed to reduce label noise and ensure data quality. We conduct extensive experiments across large language models, general PRMs, and tool-specialized PRMs on ToolPRMBench. The results reveal clear differences in PRM effectiveness and highlight the potential of specialized PRMs for tool-using. Code and data will be released at https://github.com/David-Li0406/ToolPRMBench.
title ToolPRMBench: Evaluating and Advancing Process Reward Models for Tool-using Agents
topic Artificial Intelligence
Software Engineering
url https://arxiv.org/abs/2601.12294