Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Beyond annotations, the description reveals important behavior: the service is stateless, cannot verify the id, and silently ignores unknown or already-fired reminders. This is exactly the kind of fire-and-forget semantics an agent needs to handle responses correctly.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.