Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already flag destructiveHint=true and idempotentHint=true; the description adds the concrete upsert key (note + insight type + target language), which explains both why repeated calls are idempotent and what existing row gets overwritten. It does not explicitly say prior content is replaced, but the upsert wording carries most of that.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.