Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are present, so the description carries the burden. It discloses 'append-only', which is a key behavioral trait (notes cannot be overwritten/deleted), but does not mention permissions, return values, or error conditions. This is adequate for a simple write tool but leaves gaps.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.