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arXiv · 2610.03769

Bayes-Sufficient Compression Is Not Enough: How Does Communication Help Multi-Agent Systems?

Yi Xie·Zhanke Zhou·Yi Fan·Yong Ge·Bo Han·Bo Liu
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Abstract

Multi-agent LLM systems pair a sender with broad context and an executor with a limited local view. We study when a short message improves the executor's next decision, when raw context is preferable, and when a stronger sender helps. Our framework, \emph{receiver-relative bounded coordination}, expresses message utility as receiver gain minus protocol tax. Compression beats raw context when tax savings exceed losses from omitted information and decoder mismatch. Even \emph{Bayes-sufficient} compression can fail when a bounded executor cannot use its surface form. A three-stage decomposition separates externalization, absorption, and \emph{action closure}, explaining how errors remain after the correct content reaches the receiver. Under a single-crossing condition, sender upgrades help above a receiver-burden threshold. Across six benchmarks, the same Qwen protocol raises ContextBench joint accuracy from $0.633$ to $0.775$ but lowers ToolSandbox from $0.889$ to $0.653$. Fixed-message replay reveals closure failures despite correct artifact recovery. These results guide an inference-time selector that improves the accuracy-cost frontier on the evaluated communication regimes.

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Yi Xie, Zhanke Zhou, Yi Fan, Yong Ge, Bo Han, Bo Liu. 2026-09-29. Bayes-Sufficient Compression Is Not Enough: How Does Communication Help Multi-Agent Systems?. https://arxiv.org/abs/2610.03769

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