Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish readOnlyHint=false, destructiveHint=false, and idempotentHint=false, so the description is not required to repeat those. It adds valuable behavioral context beyond the annotations: the operation fails with specific error categories (not found, not the author, or validation) and returns the updated post. This is meaningful and non-redundant.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.