Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds 'unauthenticated' which is a new behavioral trait beyond annotations. No contradiction. However, it does not disclose any other behaviors (e.g., what happens when engine is invalid).
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.