Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true, idempotentHint=true, and readOnlyHint=false. The description adds the context of clearing sensitive data and the action of deletion, but doesn't disclose additional behavioral details beyond what annotations imply, such as whether deletion is reversible or the outcome of deleting a non-existent key.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.