Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations supplied, the description carries the full burden of behavioral disclosure. It does state the core behavior: parse the expression, explain the schedule, and compute the next 5 run times in ISO format. However, it omits details such as timezone handling, behavior on invalid expressions, or whether standard extensions like @daily are supported, which would make behavior more transparent.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.