Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's simplicity (one parameter, no output schema) and the presence of annotations for destructive and idempotent behavior, the description adequately covers the what, when, and how. It could mention the result of deleting a non-existent key, but the idempotent annotation implies a no-op, so the current description is sufficient for a tool this straightforward.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.