Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructiveHint=true, idempotentHint=false, and openWorldHint=true, so the safety profile is known. The description adds nothing beyond that — it does not say whether deletion is permanent, whether messages/notes cascade, or whether confirmation is required, which matters for a destructive irreversible operation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.