Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint and destructiveHint, and the description adds meaningful behavior beyond them: suspended periods are 'withheld and counted, never silently dropped,' and a fully-suspended span 'fails with the reason.' It also discloses licensing, cost, and authentication requirements, which is useful operational context.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.