Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden, and it does disclose one real behavioral trait: cancellation can interrupt a running wait. It says nothing about whether cancel is idempotent or reversible, what status reports, or how long tasks persist, which are the gaps that matter for a mutation path.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.