Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations declare destructiveHint=true, so the agent knows updates can overwrite. The description notes that note is replaced entirely and emoji/name can be kept, which adds context beyond annotations. It doesn't mention permissions, reversibility, or rate limits, but covers the mutation semantics reasonably.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.