Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's simplicity (two parameters, one enum) and the presence of an output schema, the description covers the essential aspects: purpose, rates, source, and when to use. It does not explain the async behavior, but the schema already does, so this is adequately complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.