Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
With an output schema present and annotations covering safety, the description need not explain return values, and it doesn't. For a single-optional-param lookup tool it covers purpose, trigger, method semantics, auth, and default behavior — nothing an agent needs is missing.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.