Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a single-parameter read-only tool with a rich schema, an output schema, and clear annotations, the description covers all needed essentials: what it returns, where the id comes from, invalid-id behavior, data source, and authentication. Nothing an agent needs is missing.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.