Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Beyond the readOnly/idempotent/closed-world annotations, the description discloses substantial behavioral rules: masking of cards, review-account behavior with no vendor contact, and the exact conditions under which a vendor's contact details, credits and certification statuses are revealed. It also explicitly states that no pricing is returned, which prevents a wrong assumption about payload content.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.