Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description adds behavioral context beyond the annotations: it specifies the possible status values, that a result is only returned at a terminal state, and that polling is expected. Annotations already cover read-only/idempotent/non-destructive behavior, so this additional return-semantics detail earns solid credit.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.