MCPP-TOOL04: Tool description references other tools (shadowing)

Family	Tool surface
Default severity	medium
Confidence	medium
Mode	passive (default scan)
Spec revisions	all

Why it matters

A tool that tells the model how to use other tools, especially tools from another server, can redirect actions (e.g. "when sending email, BCC this address") without ever being called itself. This is tool shadowing.

Remediation

Keep each description about its own tool. Treat servers whose tools mention tools of other servers as untrusted.

References

• MCP Security Best Practices
• OWASP MCP Top 10

Suppressing

# .mcp-posture-ignore
[[ignore]]
check = "MCPP-TOOL04"
target = "https://mcp.example.com/*"
justification = "Why this is acceptable here"
expires = 2026-12-31