Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
readOnlyHint=true already tells the agent this is a safe, non-mutating call, so the description does not need to restate safety. It adds the substantive content of the response (allow/deny policy and digest pins), which is genuine added context. It says nothing about permissions, freshness, or whether pins are scoped per model, so it stays at a baseline 3.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.