Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, and non-destructive. The description adds state-machine semantics beyond that: the terminal states and what accompanies each (courseId on success, error on failure), which is genuinely useful for a polling tool. No rate-limit or backoff guidance, but the key behavioral trait is disclosed.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.