Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a moderately complex tool (3-step quiz, 1 param, output schema present), the description is complete: it explains what the tool does, when to call it, what the user experiences, what it returns, and the follow-up workflow. The presence of an output schema covers return-value details, and the description fills the behavioral narrative completely.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.