Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden. It discloses that this is a preview ('would be sent' and '(preview)'), which implies no email is actually sent. However, it does not explicitly state whether the operation is read-only or if any state is changed, and it lacks details about permissions or error behavior.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.