Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare this as a safe, idempotent, closed-world read, so safety behavior is covered. The description does add useful context beyond that: results are 'bounded' and 'source-backed' with 'source dates,' and some values may be in 'unknown states,' which tells the agent to expect incomplete data. It stops short of describing coverage limits, staleness windows, or granularity.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.