Getting the Source Right, Not Just the Fact: Source-Aware Verification for MCP Agents

This post introduces ProvenanceGuard, a source-aware verification layer for Model Context Protocol (MCP) agents. It addresses the failure mode of cross-source conflation by ensuring that claims made by an agent are attributed to the correct source, rather than just being supported by any source in the pooled evidence. ProvenanceGuard processes agent traces to decompose answers into claims, identify relevant sources, verify claim support using NLI models, and check attribution against the answer's stated or implied source. It also includes a repair loop for blocked answers. The system was evaluated on a medical agent and demonstrated high accuracy in catching unsupported claims and source attribution errors, with a focus on conservative decision-making for data-sensitive review.