Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It usefully signals this is a read operation whose return varies by job state (status, progress, or finished report), which is real behavioral information. It says nothing about authentication needs, error behavior for an unknown/expired job_id, or result retention/rate limits.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.