Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full behavioral burden. 'List all active network mock rules' conveys a read-only operation and explicitly scopes results to active rules, which is useful. It could be more explicit about having no side effects, but the verb 'list' makes the non-mutating behavior reasonably clear.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.