Ask Now, Use Later: Benchmarking the Proactivity Gap in Long-Lived LLM Agents

Bin Wu, Guanyun Zou, Bingbing Wang, Huan Zhao, Chuan Shi


Abstract
A long-lived LLM agent, such as OpenClaw, earns its value by acting on a user’s preferences and constraints across sessions, not just the current request. Yet today’s agents keep what a user volunteers but rarely ask for what stays unspoken, leaving a proactivity gap in long-lived LLM agents: an agent cannot act on a preference it never obtained. As users delegate more of their affairs to agents, the impact of this gap grows. We isolate one concrete, controllable slice of this gap as Ask-to-Remember (ATR): the agent decides whether to ask now for a reusable user preference that the current task does not need but a later session with the same user will. ATR is hard even to evaluate: the right question is underdetermined and its payoff deferred to tasks that may never arise. ATRBench, to the best of our knowledge the first ATR benchmark, makes it measurable by fixing each user’s preferences as hidden ground truth, so success demands asking, not recall. Across eight frontier LLM agents, defaults fall at least 62 points below an oracle handed the relevant preference, and prompting closes little of it. Diagnostics identify acquisition as the bottleneck. ATRBench surfaces this proactivity gap in current agents and offers a diagnostic testbed for closing it.
Anthology ID:
2026.emnlp-main.1505
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
Note:
Pages:
34367–34403
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1505/
DOI:
Bibkey:
Cite (ACL):
Bin Wu, Guanyun Zou, Bingbing Wang, Huan Zhao, and Chuan Shi. 2026. Ask Now, Use Later: Benchmarking the Proactivity Gap in Long-Lived LLM Agents. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 34367–34403, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Ask Now, Use Later: Benchmarking the Proactivity Gap in Long-Lived LLM Agents (Wu et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1505.pdf