MC-Search: Evaluating and Enhancing Multimodal Agentic Search with Structured Long Reasoning Chains

Fuente: arXiv
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Autori principali: Ning, Xuying, Fu, Dongqi, Wei, Tianxin, Ai, Mengting, Zou, Jiaru, Li, Ting-Wei, Tong, Hanghang, Zhu, Yada, Hamann, Hendrik, He, Jingrui
Natura: Preprint
Pubblicazione: 2026
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author Ning, Xuying
Fu, Dongqi
Wei, Tianxin
Ai, Mengting
Zou, Jiaru
Li, Ting-Wei
Tong, Hanghang
Zhu, Yada
Hamann, Hendrik
He, Jingrui
author_facet Ning, Xuying
Fu, Dongqi
Wei, Tianxin
Ai, Mengting
Zou, Jiaru
Li, Ting-Wei
Tong, Hanghang
Zhu, Yada
Hamann, Hendrik
He, Jingrui
contents With the increasing demand for step-wise, cross-modal, and knowledge-grounded reasoning, multimodal large language models (MLLMs) are evolving beyond the traditional fixed retrieve-then-generate paradigm toward more sophisticated agentic multimodal retrieval-augmented generation (MM-RAG). Existing benchmarks, however, mainly focus on simplified QA with short retrieval chains, leaving adaptive planning and multimodal reasoning underexplored. We present MC-Search, the first benchmark for agentic MM-RAG with long, step-wise annotated reasoning chains spanning five representative reasoning structures. Each example specifies sub-questions, retrieval modalities, supporting facts, and intermediate answers, with fidelity ensured by HAVE (Hop-wise Attribution and Verification of Evidence), resulting in 3,333 high-quality examples averaging 3.7 hops. Beyond answer accuracy, MC-Search introduces new process-level metrics for reasoning quality, stepwise retrieval and planning accuracy. By developing a unified agentic MM-RAG pipeline, we benchmark six leading MLLMs and reveal systematic issues such as over- and under-retrieval and modality-misaligned planning. Finally, we introduce Search-Align, a process-supervised fine-tuning framework leveraging verified reasoning chains, showing that our data not only enables faithful evaluation but also improves planning and retrieval fidelity in open-source MLLMs.
format Preprint
id arxiv_https___arxiv_org_abs_2603_00873
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle MC-Search: Evaluating and Enhancing Multimodal Agentic Search with Structured Long Reasoning Chains
Ning, Xuying
Fu, Dongqi
Wei, Tianxin
Ai, Mengting
Zou, Jiaru
Li, Ting-Wei
Tong, Hanghang
Zhu, Yada
Hamann, Hendrik
He, Jingrui
Artificial Intelligence
With the increasing demand for step-wise, cross-modal, and knowledge-grounded reasoning, multimodal large language models (MLLMs) are evolving beyond the traditional fixed retrieve-then-generate paradigm toward more sophisticated agentic multimodal retrieval-augmented generation (MM-RAG). Existing benchmarks, however, mainly focus on simplified QA with short retrieval chains, leaving adaptive planning and multimodal reasoning underexplored. We present MC-Search, the first benchmark for agentic MM-RAG with long, step-wise annotated reasoning chains spanning five representative reasoning structures. Each example specifies sub-questions, retrieval modalities, supporting facts, and intermediate answers, with fidelity ensured by HAVE (Hop-wise Attribution and Verification of Evidence), resulting in 3,333 high-quality examples averaging 3.7 hops. Beyond answer accuracy, MC-Search introduces new process-level metrics for reasoning quality, stepwise retrieval and planning accuracy. By developing a unified agentic MM-RAG pipeline, we benchmark six leading MLLMs and reveal systematic issues such as over- and under-retrieval and modality-misaligned planning. Finally, we introduce Search-Align, a process-supervised fine-tuning framework leveraging verified reasoning chains, showing that our data not only enables faithful evaluation but also improves planning and retrieval fidelity in open-source MLLMs.
title MC-Search: Evaluating and Enhancing Multimodal Agentic Search with Structured Long Reasoning Chains
topic Artificial Intelligence
url https://arxiv.org/abs/2603.00873