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 important post-condition: the associated number keeps ringing default routing after deletion. It omits whether deletion is irreversible, whether it fails when the ring group is referenced by a call flow, required permissions, and what the response contains.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.