Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly/destructive/idempotent hints, so the 'strictly read-only' line is mostly redundant. The description nonetheless adds real behavioral value the annotations cannot: that this is a polling endpoint, that job_id is a background handle, and the status state machine (queued|running|completed|failed).
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.