Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover readOnlyHint and destructiveHint, so the description's main contribution is the caveat 'A request is not proof of payment.' This is valuable behavioral context beyond annotations, warning the agent that a listed request may not be a completed transaction. It also clarifies 'owned' scope, but doesn't discuss ordering, rate limits, or response details, which are acceptable given the safety annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.