Simulating the Lateral Reader for News Trustworthiness Reports with an Iterative Multi-Agent RAG System

Abstract

Readers of online news often lack the time and domain expertise required to verify unfamiliar claims and sources. Professional fact-checkers address this gap through lateral reading, an iterative workflow of asking investigative questions, searching for external evidence, and synthesizing findings with attribution. We present an iterative multi-agent Retrieval-Augmented Generation (RAG) system that operationalizes this workflow for the TREC 2025 DRAGUN Track. Given a news article, specialized agents (1) generate investigative queries, (2) retrieve and filter evidence from the MS MARCO V2.1 Segmented Corpus using a three-stage retriever (BM25+RM3, cross-encoder reranking, and LLM-based selection), and (3) apply an information-sufficiency evaluator that decides whether additional searching is required before writing. The final report generator produces a 250-word trustworthiness report grounded in retrieved segments, guided by automatically generated critical investigative questions. On the official DRAGUN rubric-based evaluation with 30 news articles, our system using GPT-4.1 ranked first on report generation quality, achieving the highest mean supportive score (0.230) with low contradiction (0.013).