Two Heads are Better Than One: Test-time Scaling of Multi-agent Collaborative Reasoning

Can Jin, Hongwu Peng, Qixin Zhang, Yang Zhou, Yujin Tang, Tong Che, Dimitris N. Metaxas


Abstract
Test-Time Scaling has emerged as a powerful method to extend the reasoning capabilities of Large Language Models. However, single-agent TTS faces significant scalability bottlenecks, as excessively long reasoning traces lead to increased inference costs and stability issues caused by context management failures. To address these limitations, we propose leveraging Multi-Agent Systems as a structural upgrade to standard TTS. By decomposing monolithic reasoning chains into distinct, manageable contexts across multiple agents, MAS offers a more robust framework for scaling reasoning. We validate this approach by introducing M500, a dataset comprising 500 high-quality multi-agent, multi-turn collaborative reasoning traces generated via DeepSeek-R1. Through Supervised Fine-Tuning on M500, we enable open-source models to internalize collaborative reasoning patterns and show improved TTS performance in MAS. Furthermore, we propose an adaptive scaling strategy incorporating a “CEO” agent to dynamically guide the reasoning process and optimize collaboration depth. Extensive experiments within the AgentVerse framework demonstrate that our fine-tuned models, Qwen2.5-32B-MAS and Phi4-14B-MAS, significantly outperform their base counterparts.
Anthology ID:
2026.findings-emnlp.427
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
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
8984–9004
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.427/
DOI:
Bibkey:
Cite (ACL):
Can Jin, Hongwu Peng, Qixin Zhang, Yang Zhou, Yujin Tang, Tong Che, and Dimitris N. Metaxas. 2026. Two Heads are Better Than One: Test-time Scaling of Multi-agent Collaborative Reasoning. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 8984–9004, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Two Heads are Better Than One: Test-time Scaling of Multi-agent Collaborative Reasoning (Jin et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.427.pdf