Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's simplicity (1 parameter, annotations present, no output schema), the description is sufficient. It explains the input source and the output relationship to check_phone_number, providing enough context for an agent to use the tool correctly. Slight deduction for not detailing the exact return structure, but this is mitigated by the 'same data as check_phone_number' reference.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.