Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, non-destructive, making the safety bar low; the description still adds real value by disclosing that the EIN is never returned (only presence), that the result mirrors the dashboard's text registration page, and how `known`/`missing`/`next_question` behave. It omits nothing contradicting the annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.