Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations only say the operation is not read-only, not idempotent, and not destructive. The description adds materially useful behavioral context: human vetting, credentials delivered to the supplied email, the absence of a key requirement, and a 3-per-day per-address rate limit. This goes well beyond what annotations alone convey.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.