AAMAS Conference 2026 Conference Paper
- Yuheng Jing
- Kai Li
- Bingyun Liu
- Ziwen Zhang
- Zhe Wu
- Yifan Zhang
- Junliang Xing
- Jian Cheng
In multi-agent systems, building agents capable of seamlessly collaborating with unknown partners is a long-standing research goal. Existing approaches primarily generate a diverse population of partners and then train an agent against this population to master various cooperation conventions. However, these approaches are often hindered in two aspects: (1) They heavily rely on taskspecific training; (2) Their trained agents lack adaptability at test time. In this paper, we investigate how to leverage Large Language Models (LLMs) to build agents capable of foresighted coordination, addressing the challenges faced by existing work. To facilitate structured reasoning mechanisms, we introduce DTPAgent, a novel LLM-driven Decision-Time Planning (DTP) framework. Within this framework, LLMs, without relying on task-specific training and solely through in-context learning, estimate the partner policy and the transition-reward function to model the full dynamics of the environment. Based on these LLM-driven modelings, DTPAgent This work is licensed under a Creative Commons Attribution International 4. 0 License. Proc. of the 25th International Conference on Autonomous Agents and Multiagent Systems (AAMAS 2026), C. Amato, L. Dennis, V. Mascardi, J. Thangarajah (eds.), May 25 – 29, 2026, Paphos, Cyprus. © 2026 International Foundation for Autonomous Agents and Multiagent Systems (www. ifaamas. org). https: //doi. org/10. 65109/XALP4331 simulates a range of possible trajectories to dynamically search for the most advantageous policy at each timestep. We demonstrate on the popular benchmark, Overcooked, that DTPAgent, built with small-scale LLMs, effectively outperforms various types of baselines when faced with unseen partners. Our DTPAgent also exhibits a scalable property that existing agents lack: the ability to translate test-time computation into improved performance.