DIANOIA: Diagnostic Decomposition and Joint Optimization for Multi-Agent Reasoning

Yiming Yang, Zhuoyuan Li, Fanxiang Zeng, Hao Fu, Yue Liu


Abstract
Multi-agent LLM systems can outperform single-agent baselines, yet practitioners still cannot predict which design works for a new task or diagnose why one fails. We argue this gap persists largely because the field lacks a diagnostic framework with measurable primitives and testable predictions. We introduce DIANOIA, a three-channel decomposition of multi-agent reasoning gain into coverage, fidelity, and synthesis, each of which is empirically measurable. From this decomposition, we propose a diagnostic protocol that forms qualitative hypotheses about bottleneck channels for tasks with measurable quality signals. We instantiate the protocol as a multi-agent system whose three components mirror the channels: role-diverse proposers for coverage, execution- or pseudo-verification-grounded review for fidelity, and iterative synthesis. On GSM8K, MBPP, and BFCL-SP, our method outperforms strong multi-agent baselines under matched standard configurations; on MBPP, it matches the strongest baseline with approximately 5× fewer tokens and dominates the measured accuracy–token Pareto frontier. Full-scale MBPP replications on Qwen, DeepSeek, and Gemini consistently improve over the corresponding single-model baseline. A prospective held-out evaluation on VitaBench, whose bottleneck hypothesis was recorded before running DIANOIA, improves pass rate from 29.5% to 45.0%. DIANOIA reframes multi-agent design as channel-aware resource allocation: diagnose the likely bottleneck, then invest tokens accordingly.
Anthology ID:
2026.emnlp-main.1446
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
33019–33053
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1446/
DOI:
Bibkey:
Cite (ACL):
Yiming Yang, Zhuoyuan Li, Fanxiang Zeng, Hao Fu, and Yue Liu. 2026. DIANOIA: Diagnostic Decomposition and Joint Optimization for Multi-Agent Reasoning. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 33019–33053, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
DIANOIA: Diagnostic Decomposition and Joint Optimization for Multi-Agent Reasoning (Yang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1446.pdf