Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Goes beyond the annotations by disclosing the create-on-first-use side effect for cookbooks, the default-cookbook fallback, that a recipe may live in several cookbooks, and that a repeat save only updates the note. That last point softens the destructiveHint=true annotation but does not contradict it outright, since overwriting a note is still a mutation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.