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: the call is cheap and does not hash model artifacts. It leaves out whether the operation is strictly read-only, whether it may touch a running generation, or what the returned state contains, so the safety and cost profile is only partially covered.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.