Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Discloses that the secret is shown once, never stored, not idempotent, returns specific fields, and error behavior. Adds context beyond annotations, which only provide readOnlyHint and destructiveHint. Note: destructiveHint=false might be contradicted by 'invalidating the old one', but description is still transparent.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.