Exploring Agentic Tool-Calling Decisions via Uncertainty-Aligned Reinforcement Learning

Yijin Zhou, Linqian Zeng, Xiaoya Lu, Wenyuan Xie, Dongrui Liu, Junchi Yan, Jing Shao


Abstract
Large language model (LLM)-based agents often make suboptimal tool-use decisions, including unsupported tool invocation and hallucinated direct responses, which may accumulate errors throughout multi-step interactions. Existing approaches mainly improve these behaviors through inference-time correction or coarse-grained reward signals based on decision outcomes and structured checklists, leaving the uncertainty characteristics of agent decisions underexplored. We observe that decision-oriented reinforcement learning tends to weaken the uncertainty separation between correct and incorrect actions, resulting in overconfident mistakes and weaker exploration signals. Therefore, we propose TRUST, which incorporates uncertainty quantification into reward design as a repulsive force for maintaining uncertainty separation, and labels lightweight key-turn annotations for unified post-training of multi-turn trajectories. Experimental results across diverse tool-use benchmarks show that TRUST consistently enhances both decision quality and agent performance while maintaining more reliable uncertainty estimates during optimization.
Anthology ID:
2026.findings-emnlp.513
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:
10734–10756
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.513/
DOI:
Bibkey:
Cite (ACL):
Yijin Zhou, Linqian Zeng, Xiaoya Lu, Wenyuan Xie, Dongrui Liu, Junchi Yan, and Jing Shao. 2026. Exploring Agentic Tool-Calling Decisions via Uncertainty-Aligned Reinforcement Learning. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 10734–10756, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Exploring Agentic Tool-Calling Decisions via Uncertainty-Aligned Reinforcement Learning (Zhou et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.513.pdf