Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a 5-parameter, 1-required tool with a full schema and an output schema, the description covers the call trigger, content standards, and the rationale for optional fields. The only unresolvable details (site code handling, return value) are already covered by the schema and output schema respectively.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.