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Main Authors: Sun, Yuqi, Meng, Tianqin, Liu, George, Panwar, Yashraj, Chaudhry, Lakshya, Ilham, Munasib, Chadha, Aman
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2604.23057
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author Sun, Yuqi
Meng, Tianqin
Liu, George
Panwar, Yashraj
Chaudhry, Lakshya
Ilham, Munasib
Chadha, Aman
author_facet Sun, Yuqi
Meng, Tianqin
Liu, George
Panwar, Yashraj
Chaudhry, Lakshya
Ilham, Munasib
Chadha, Aman
contents We investigate whether explicit belief graphs improve LLM performance in cooperative multi-agent reasoning. Through 3,000+ controlled trials across four LLM families in the cooperative card game Hanabi, we establish four findings. First, integration architecture determines whether belief graphs provide value: as prompt context, graphs are decorative for strong models and beneficial only for weak models on 2nd-order Theory of Mind (80% vs 10%, p<0.0001, OR=36.0); when graphs gate action selection through ranked shortlists, they become structurally essential even for strong models (100% vs 20% on 2nd-order ToM, p<0.001). Second, we identify "Planner Defiance," a model-family-specific failure where LLMs override correct planner recommendations at partial competence (90% override, replicated N=20); Gemini models show near-zero defiance while Llama 70B shows 90%, and models distinguish factual context (deferred to) from advisory recommendations (overridden). Third, full-game evidence confirms inter-agent conventions (+128% over baseline, p=0.003) outperform all single-agent interventions, and individual belief-graph components must be combined to produce gains. Fourth, preliminary scaling analysis (N=10/cell, exploratory) suggests graph depth has diminishing returns: shallow graphs provide the best cost-benefit ratio, while deeper ToM graphs appear harmful at larger player counts (-1.5 pts at 5-player, p=0.029).
format Preprint
id arxiv_https___arxiv_org_abs_2604_23057
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Don't Make the LLM Read the Graph: Make the Graph Think
Sun, Yuqi
Meng, Tianqin
Liu, George
Panwar, Yashraj
Chaudhry, Lakshya
Ilham, Munasib
Chadha, Aman
Artificial Intelligence
We investigate whether explicit belief graphs improve LLM performance in cooperative multi-agent reasoning. Through 3,000+ controlled trials across four LLM families in the cooperative card game Hanabi, we establish four findings. First, integration architecture determines whether belief graphs provide value: as prompt context, graphs are decorative for strong models and beneficial only for weak models on 2nd-order Theory of Mind (80% vs 10%, p<0.0001, OR=36.0); when graphs gate action selection through ranked shortlists, they become structurally essential even for strong models (100% vs 20% on 2nd-order ToM, p<0.001). Second, we identify "Planner Defiance," a model-family-specific failure where LLMs override correct planner recommendations at partial competence (90% override, replicated N=20); Gemini models show near-zero defiance while Llama 70B shows 90%, and models distinguish factual context (deferred to) from advisory recommendations (overridden). Third, full-game evidence confirms inter-agent conventions (+128% over baseline, p=0.003) outperform all single-agent interventions, and individual belief-graph components must be combined to produce gains. Fourth, preliminary scaling analysis (N=10/cell, exploratory) suggests graph depth has diminishing returns: shallow graphs provide the best cost-benefit ratio, while deeper ToM graphs appear harmful at larger player counts (-1.5 pts at 5-player, p=0.029).
title Don't Make the LLM Read the Graph: Make the Graph Think
topic Artificial Intelligence
url https://arxiv.org/abs/2604.23057