Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. 'Stream updates' hints at an incremental/streaming response, but nothing is said about whether the call blocks until task completion, how updates are delivered or terminated, what happens on error, or how the timeout parameter behaves.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.