Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint and openWorldHint. The description adds valuable details: the output format (JPEG), the frequency-based sizing behavior, and a per-call point cost. It does not contradict the annotations, though it omits return transport details like URL vs base64.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.