Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate write operation (readOnlyHint=false) and non-destructive (destructiveHint=false). Description adds that it returns the new record ID, which is not in annotations. However, idempotentHint=true conflicts with the description's implication of creating a new record each call, but description does not explicitly claim idempotency.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.