Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple pure function with one well-documented parameter and an output schema, the description is largely complete: it covers purpose, input cardinality, use cases, and local execution. It could still mention what happens with a single coordinate or edge-case behavior, but the low complexity means these are minor omissions.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.