Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It discloses that the tool blocks while waiting, returns a presigned download URL, and that polling is repeatable with the same session_id so the capture URL can be reused. It does not describe timeout failure behavior, but the blocking nature is implied and the reuse property is a valuable behavioral disclosure.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.