Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden of disclosing behavior, but it reveals almost nothing. It does not state whether the operation is read-only, what the response structure is, whether counts are grouped, or any side effects (e.g., performance implications).
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.