MCPP-PIN01: Tool surface item added since the baseline

Family	Rug-pull pinning
Default severity	medium
Confidence	high
Mode	passive (default scan)
Spec revisions	all

Why it matters

A new tool, prompt or resource appeared after the server was reviewed and pinned. New tools are exposed to the agent without any review.

Remediation

If the change is expected (you updated the server), review the diff and refresh the lock file with mcp-posture pin. If not, stop using the server: definitions that change after approval are how rug pulls work.

References

• MCP Security Best Practices
• OWASP MCP Top 10

Suppressing

# .mcp-posture-ignore
[[ignore]]
check = "MCPP-PIN01"
target = "https://mcp.example.com/*"
justification = "Why this is acceptable here"
expires = 2026-12-31