Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), and the description adds genuinely new behavioral facts: the text-layer limitation with no OCR fallback, the $0.005 per successful call price, free failures, and a keyless free trial tier. That is real context an agent cannot get from the annotations or schema.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.