Inspect an MCP tool manifest before attaching it to an agent

Description and use

Verifying MCP tool manifests locally with a static scanner detects selection‑manipulation language and blocks unsafe toolsets before attachment to an agent.

Problem

Operators need to verify MCP tool manifests for malicious or misleading metadata before enabling them in an agent, to prevent unintended tool invocation or manipulation.

Outcome

The workflow demonstrates that a local static scan can detect selection‑manipulation language in a tool manifest, blocking or flagging it before attachment. The example shows a BLOCK result with a high finding (BB013) for the synthetic manifest.

Workflow

• Download the tools-list.json and its .sha256 checksum using curl or PowerShell.
• Verify the checksum with sha256sum or Get-FileHash to ensure file integrity.
• Run the pinned Agent Scan CLI: npx -y @backbond/[email protected] vet-tools --stdin < tools-list.json (or equivalent PowerShell cmd).
• Interpret the exit code: 0 = no_blocking_finding, 1 = block, 3 = review.
• If blocked or review, investigate the findings and decide whether to modify or reject the manifest before attachment.
• If no_blocking_finding, proceed to attach the tools to the agent.
• Document the scan result and any operator decisions for audit purposes.

Evidence

For this exact synthetic fixture, the verified result is BLOCK with one high finding, BB013, and exit code 1.

Source

The pre-attachment gate returns block (exit 1), review (exit 3), or no_blocking_finding (exit 0).

Source