Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only, idempotent and non-destructive safety, and the description adds real behavioral context on top: no account needed, evidence includes coverage and dates, ambiguous identity returns candidate choices rather than an error, and 'not indexed does not mean no AI visibility' pre-empts a false negative reading. It also discloses the one-cited-page limit when supported.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.