Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a single-parameter lookup with a rich schema, supportive annotations, and an output schema, the description is complete. It states what the tool does, how to use the result, and the operational cost, leaving no critical gap for an agent to call it correctly.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.