Beyond Fact-Checking: Source-Aware Verification for MCP Agents

Introduction

Traditional LLM verification tools focus on whether a claim is supported by any evidence in the context window. However, modern MCP-enabled agents gather information from multiple sources—search tools, databases, records—and synthesize answers from disparate inputs. This creates a subtle but significant problem: even when a fact exists somewhere in the evidence pool, attributing it to the wrong source can produce dangerously misleading responses.

The failure mode known as cross-source conflation occurs when an answer correctly reflects a truth but incorrectly links it to its origin. For example, a customer support bot might state "According to the account record, this plan includes a 30‑day refund window," even though the refund policy lives in a different document. When the system blends evidence pools without tracking provenance, such misattributions become invisible and potentially harmful in data‑sensitive applications.

Our research introduces ProvenanceGuard, a post‑generation verification layer that operates atop black‑box MCP agents. Unlike traditional verifiers that collapse evidence into a single anonymous context, ProvenanceGuard preserves the complete MCP trace—including tool outputs and their source identifiers—without requiring agent retraining.

The system performs five sequential checks on each generated claim: it identifies the most relevant source for the claim, validates whether that source actually supports it, compares the supporting source with the one named or implied by the answer, and finally emits a per‑claim source verdict along with a confidence score. This granular approach distinguishes between mere factual correctness and genuine source fidelity.

Why it matters for GPU/AI infrastructure: As AI workloads scale across distributed GPU clusters, the reliability of agent-driven workflows grows increasingly important. Wrong attributions can lead to incorrect decisions, compliance violations, and eroded trust in automated systems. ProvenanceGuard provides a foundational guardrail for enterprise deployments where auditability and regulatory compliance are paramount.