Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already disclose readOnly, idempotent, and non-destructive behavior, so the description does not need to restate it. It adds the kebab-case naming convention and lists what the result contains, but that list is largely return-value information which the output schema already covers. No auth, error, or rate-limit behavior is described.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.