Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden. It does convey that the operation is a non-mutating 'Return' and that it reveals 'current effective permissions,' which is useful context beyond the bare tool name. However, it omits prerequisites, error behavior, and what exactly 'metadata' includes.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.