Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a one-parameter read-only tool with an output schema, the description is complete: it explains what is fetched, how it is identified, what is returned, the visibility constraint, and the relationship to the sibling listing tool. No missing information an agent needs to invoke it correctly.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.