Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden and discloses almost nothing: it doesn't say whether a failed check throws an error or returns a failure status, whether it times out, or what auth is required beyond 'authorized'. Only the read-only nature is weakly implied by 'check'.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.