Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given zero parameters, no output schema, and annotations covering safety, the description provides sufficient guidance for correct invocation: what the tool returns (coverage and freshness), when to call it, and how to avoid misinterpreting the absence of coverage. Slightly more detail on return format would be nice, but the tool's simplicity makes this largely complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.