MASS-RAG: Multi-Agent Synthesis Retrieval-Augmented Generation

Xingchen Xiao, Heyan Huang, Runheng Liu, Jincheng Xie


Abstract
Large language models (LLMs) are widely used in retrieval-augmented generation (RAG) to incorporate external knowledge at inference time. However, when retrieved contexts are noisy, incomplete, or heterogeneous, a single generation process often struggles to reconcile evidence effectively. We propose MASS-RAG, a multi-agent synthesis approach to retrieval-augmented generation that structures evidence processing into multiple role-specialized agents. MASS-RAG applies distinct agents for evidence summarization, evidence extraction, and reasoning over retrieved documents, and combines their outputs through a dedicated synthesis stage to produce the final answer. This design exposes multiple intermediate evidence views, allowing the model to compare and integrate complementary information before answer generation. Experiments on four benchmarks show that MASS-RAG consistently improves performance over strong RAG baselines, particularly in settings where relevant evidence is distributed across retrieved contexts.
Anthology ID:
2026.findings-acl.480
Volume:
Findings of the Association for Computational Linguistics: ACL 2026
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
Findings
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Publisher:
Association for Computational Linguistics
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Pages:
9865–9883
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URL:
https://preview.aclanthology.org/ingest-acl/2026.findings-acl.480/
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Cite (ACL):
Xingchen Xiao, Heyan Huang, Runheng Liu, and Jincheng Xie. 2026. MASS-RAG: Multi-Agent Synthesis Retrieval-Augmented Generation. In Findings of the Association for Computational Linguistics: ACL 2026, pages 9865–9883, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
MASS-RAG: Multi-Agent Synthesis Retrieval-Augmented Generation (Xiao et al., Findings 2026)
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https://preview.aclanthology.org/ingest-acl/2026.findings-acl.480.pdf
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