Where Do Deep-Research Agents Go Wrong? Span-Level Error Localization in Agent Trajectories

Hugging Face Daily Papers Papers

Summary

This paper introduces a claim-centric auditing framework for identifying error spans in deep-research agent trajectories, along with a new benchmark TELBench, improving process-level reliability assessment.

Deep-research agents solve tasks through long trajectories of search, tool use, evidence inspection, and answer synthesis. Evaluation based on final answers shows whether an agent succeeds, but not which parts of the trajectory make the answer unreliable. We study span-level error localization for deep-research agents. We collect 2,790 real trajectories from two agent frameworks, three backbone models, and three benchmarks, convert raw logs into semantic spans, and annotate harmful error spans through LLM-assisted expert review. From these annotations, we build TELBench, a 1,000-instance benchmark for identifying error spans among normal exploration, failed searches, tentative hypotheses, and harmless noise. We further propose DRIFT, a claim-centric auditing framework that tracks agent claims, checks their support in trajectory evidence, and marks spans where unsupported or conflicting claims affect the answer path. Experiments across model families and auditing frameworks show that DRIFT improves span-level error localization and first-error accuracy by up to 30 percentage points. Our work provides a process-level view of reliability in deep-research agents.
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Source: https://huggingface.co/papers/2606.02060

Abstract

Deep-research agents can be audited using a claim-centric framework that identifies error spans in their reasoning trajectories, improving reliability assessment beyond just final answer evaluation.

Deep-research agentssolve tasks through long trajectories of search, tool use, evidence inspection, and answer synthesis. Evaluation based on final answers shows whether an agent succeeds, but not which parts of the trajectory make the answer unreliable. We studyspan-level error localizationfordeep-research agents. We collect 2,790 real trajectories from twoagent frameworks, threebackbone models, and three benchmarks, convert raw logs into semantic spans, and annotate harmfulerror spansthroughLLM-assisted expert review. From these annotations, we buildTELBench, a 1,000-instance benchmark for identifyingerror spansamong normal exploration, failed searches, tentative hypotheses, and harmless noise. We further proposeDRIFT, aclaim-centric auditingframework that tracks agent claims, checks their support intrajectory evidence, and marks spans where unsupported or conflicting claims affect the answer path. Experiments across model families and auditing frameworks show thatDRIFTimprovesspan-level error localizationand first-error accuracy by up to 30 percentage points. Our work provides a process-level view of reliability indeep-research agents.

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