Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description must disclose behavioral traits. It only states 'List all registered agents,' which implies a read-only operation, but it does not explain pagination, rate limits, or whether any shared state is modified. This lack of detail is insufficient for a trustworthy tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.