Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations and no output schema, the description carries the full disclosure burden, and it does at least reveal the four fields the call returns. It stops short of stating that this is a non-mutating metadata lookup with no side effects, permissions, or cost, which is the kind of behavioural framing a zero-argument, unannotated tool should supply.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.