Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
The description is complete for a read-only lookup tool: it covers inputs, output values, edge cases, and error behavior. The output schema exists, so return values are already documented. A minor gap is that it doesn't explicitly state that sku and product_id are mutually exclusive, but the schema's 'Give this or product_id' phrasing implies it.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.