Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds operational behavior not covered by annotations: polling frequency, response fields like retry_after_seconds and next_action, and preference for structured_result. It also includes a concrete example URL, making the tool's behavior very transparent.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.