Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a 5-parameter tool with 3 enums, an output schema, and 11 siblings, the description covers purpose, when to use, when-not-to-use with named alternatives, and available filters/pagination. The output schema covers return values, so no need to restate them. Complete enough for selection and correct invocation, though the dense single-sentence structure is the only minor weakness.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.