ProvenanceGuard

ProvenanceGuard: Source-aware factuality verification for MCP-based LLM agents

Researchers introduce ProvenanceGuard, a verifier that checks factual claims in MCP-grounded LLM agent answers against their specific source provenance rather than pooled evidence. The system decomposes answers into atomic claims, routes each to its attributed source via MCP trace metadata, and applies NLI plus token-alignment checks to detect 'cross-source conflation' — where a claim is supported somewhere but attributed to the wrong source. Evaluated on 281 medical-domain MCP-agent traces, it achieves block F1 of 0.802 and source accuracy of 0.858 on held-out data, and detects all injected attribution swaps in 50 controlled clinical probes. The work establishes source attribution as an independent factuality axis distinct from standard grounding checks.