Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description adds context beyond annotations by specifying that it deletes sensitive data and pairs with other memory tools. No contradictions with annotations (destructiveHint=true, idempotentHint=true). It doesn't detail error handling (e.g., missing key), but the idempotent hint covers that.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.