Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
For a simple one-parameter tool with annotations covering destructiveness and idempotency, the description is complete. It covers usage cases, pairing, and the nature of the operation. The lack of an output schema is acceptable for a delete operation, and the description does not need to explain return values. Minor gap: it doesn't explicitly state behavior for missing keys, but idempotentHint implies safe repetition.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.