Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple list tool with one optional parameter, an output schema, and read-only annotations, the description is complete. It covers scope, ordering, fields, pagination, deprecation, authentication, and the correct sibling tool for pair-DMs, so an agent has everything needed to select and invoke it correctly.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.