Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint and non-destructive, so the safety profile is covered. The description adds genuinely non-obvious behavior: the self-check is deterministic, runs the structural detectors on a fixed sample, and returns expected flag counts, plus that the call is local-only and avoids the database.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.