Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already carry readOnly, idempotent, and non-destructive hints, so the bar is lower. The description adds useful behavioral context: a cost ($0.10), an API key requirement, and likely asset attributes (role, signed_url, versions). No contradiction with annotations exists.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.