UserBench: An Interactive Gym Environment for User-Centric Agents

Cheng Qian, Zuxin Liu, Akshara Prabhakar, Zhiwei Liu, Jianguo Zhang, Haolin Chen, Heng Ji, Weiran Yao, Shelby Heinecke, Silvio Savarese, Caiming Xiong, Huan Wang


Abstract
Large Language Model agents increasingly solve tool-use tasks, yet often fail to determine what users actually want when goals are underspecified, incremental, or indirectly expressed. We introduce **UserBench**, a controlled Gymnasium environment for evaluating proactive preference elicitation in multi-turn, tool-grounded interactions. Instantiated in travel planning, UserBench hides user preferences behind implicit natural-language cues and requires agents to ask targeted clarification questions, search structured option databases, and select user-aligned options. Evaluating leading open- and closed-source models reveals a large gap between tool execution and user understanding: models achieve high valid-search rates but elicit only a minority of hidden preferences, and even stronger models remain far below a human oracle. Further analysis shows that many additional interaction turns are broad or non-informative rather than preference-relevant. UserBench provides a reproducible testbed for studying and training user-centric agent interaction while intentionally abstracting away full travel negotiation and infeasible-constraint recovery.
Anthology ID:
2026.emnlp-main.772
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
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Pages:
17936–17966
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URL:
https://aclanthology.org/2026.emnlp-main.772/
DOI:
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Cite (ACL):
Cheng Qian, Zuxin Liu, Akshara Prabhakar, Zhiwei Liu, Jianguo Zhang, Haolin Chen, Heng Ji, Weiran Yao, Shelby Heinecke, Silvio Savarese, Caiming Xiong, and Huan Wang. 2026. UserBench: An Interactive Gym Environment for User-Centric Agents. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 17936–17966, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
UserBench: An Interactive Gym Environment for User-Centric Agents (Qian et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.772.pdf