Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It reveals part of the return shape (variables and last timing) but says nothing about whether the call is read-only, how many flows may be returned, ordering, or truncation limits — all relevant since recorded flows can accumulate.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.