TacoMAS: Test-Time Co-Evolution of Topology and Capability in LLM-based Multi-Agent Systems

Chen Xu; Yicheng Hu; Ruizi Wang; Xinyu Lin; Wenjie Wang; Dongrui Liu; Fuli Feng

title	TacoMAS: Test-Time Co-Evolution of Topology and Capability in LLM-based Multi-Agent Systems
authors	Chen Xu, Yicheng Hu, Ruizi Wang, Xinyu Lin, Wenjie Wang, Dongrui Liu, Fuli Feng
date	2026-05-10
venue	arXiv (preprint, not peer reviewed)
id	arXiv:2605.09539
upvotes	3 (Hugging Face Daily Papers, 2026-11-01)
links	abs pdf hf code
abstract	Multi-agent systems (MAS) have emerged as a promising paradigm for solving complex tasks. Recent work has explored self-evolving MAS that automatically optimize agent capabilities or communication topologies. However, existing methods either learn a topology that remains fixed at inference time or adapt only the topology or capability during inference. We empirically and theoretically show that effective test-time evolution requires jointly adapting both axes, but on different time scales: capabilities should update rapidly to handle emerging subtasks, while the topology should evolve more slowly to preserve coordination stability. We then introduce TacoMAS, a test-time co-evolution framework for dynamic MAS. TacoMAS formulates MAS inference as a task of online graph adaptation, where nodes represent agents with role-specific capabilities and edges define their communication topology. During inference, a fast capability loop updates agent expertise using trajectory-level feedback, while a slow meta-LLM-driven topology loop performs agents' birth-death operations on MAS, including edge edit, agent addition, and agent removal. We further show that this fast-slow design drives MAS evolution toward a task-conditioned stable equilibrium. Experiments on four benchmarks demonstrate that TacoMAS outperforms nearly 20 multi-agent baselines, achieving an average improvement of 13.3% over the strongest baseline. The codes are released at https://github.com/chenxu2-gif/TacoMAS-MultiAgent.

cite

@misc{xu2026tacomas,
  title={TacoMAS: Test-Time Co-Evolution of Topology and Capability in LLM-based Multi-Agent Systems},
  author={Chen Xu and Yicheng Hu and Ruizi Wang and Xinyu Lin and Wenjie Wang and Dongrui Liu and Fuli Feng},
  year={2026},
  eprint={2605.09539},
  archivePrefix={arXiv},
  url={https://arxiv.org/abs/2605.09539}
}