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 behavioral fact: no authentication is required. However it says nothing about rate limits, response shape, pagination, or whether the list is exhaustive, and the read-only nature is only implied by 'Get'.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.