Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple pure transformation tool, the description, schema, and annotations cover most of what an agent needs: parameters are documented, the operation is read-only and idempotent, and the return value is implicitly the encoded/decoded string. A slightly fuller mention of return behavior or invalid-input handling would make it fully complete.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.