Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It discloses return values (per-capita costs, total spending) and the limit parameter's default and max. However, it does not mention behavior when no filters are applied, how multiple filters interact, or pagination details. This is a moderate level of disclosure, hence a 3.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.