More Capable, Less Cooperative? When LLMs Fail At Zero-Cost Collaboration

Fuente: arXiv
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Main Authors: Yadav, Advait, Black, Sid, Sourbut, Oliver
Format: Preprint
Published: 2026
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author Yadav, Advait
Black, Sid
Sourbut, Oliver
author_facet Yadav, Advait
Black, Sid
Sourbut, Oliver
contents Large language model (LLM) agents increasingly coordinate in multi-agent systems, yet we lack an understanding of where and why cooperation failures may arise. In many real-world coordination problems, from knowledge sharing in organizations to code documentation, helping others carries negligible personal cost while generating substantial collective benefits. However, whether LLM agents cooperate when helping neither benefits nor harms the helper, while being given explicit instructions to do so, remains unknown. We build a multi-agent setup designed to study cooperative behavior in a frictionless environment, removing all strategic complexity from cooperation. We find that capability does not predict cooperation: OpenAI o3 achieves only 17% of optimal collective performance while OpenAI o3-mini reaches 50%, despite identical instructions to maximize group revenue. Through a causal decomposition that automates one side of agent communication, we separate cooperation failures from competence failures, tracing their origins through agent reasoning analysis. Testing targeted interventions, we find that explicit protocols double performance for low-competence models, and tiny sharing incentives improve models with weak cooperation. Our findings suggest that scaling intelligence alone will not solve coordination problems in multi-agent systems and will require deliberate cooperative design, even when helping others costs nothing.
format Preprint
id arxiv_https___arxiv_org_abs_2604_07821
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle More Capable, Less Cooperative? When LLMs Fail At Zero-Cost Collaboration
Yadav, Advait
Black, Sid
Sourbut, Oliver
Multiagent Systems
Artificial Intelligence
Computation and Language
Large language model (LLM) agents increasingly coordinate in multi-agent systems, yet we lack an understanding of where and why cooperation failures may arise. In many real-world coordination problems, from knowledge sharing in organizations to code documentation, helping others carries negligible personal cost while generating substantial collective benefits. However, whether LLM agents cooperate when helping neither benefits nor harms the helper, while being given explicit instructions to do so, remains unknown. We build a multi-agent setup designed to study cooperative behavior in a frictionless environment, removing all strategic complexity from cooperation. We find that capability does not predict cooperation: OpenAI o3 achieves only 17% of optimal collective performance while OpenAI o3-mini reaches 50%, despite identical instructions to maximize group revenue. Through a causal decomposition that automates one side of agent communication, we separate cooperation failures from competence failures, tracing their origins through agent reasoning analysis. Testing targeted interventions, we find that explicit protocols double performance for low-competence models, and tiny sharing incentives improve models with weak cooperation. Our findings suggest that scaling intelligence alone will not solve coordination problems in multi-agent systems and will require deliberate cooperative design, even when helping others costs nothing.
title More Capable, Less Cooperative? When LLMs Fail At Zero-Cost Collaboration
topic Multiagent Systems
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2604.07821