Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
An output schema exists, so return-format details need not be spelled out. The sole parameter is fully documented in both schema and description, annotations cover the operational profile, and the description covers purpose, usage triggers, topic content, cost, and data-access behavior. For a tool whose job is to resolve the complexity of hundreds of siblings, nothing needed to call it correctly is missing.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.