Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a 7-parameter write tool with a output schema and 100% parameter documentation, the description covers the essential non-schema aspects: purpose, beneficiary, and auth prerequisites. It doesn't describe post-submission behavior, but the output schema and annotations cover enough to make successful invocation likely.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.