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 required fields, no nested objects), the description covers the essential information: what it does and how to use the parameter. It does not mention return values, but since an output schema exists, that is acceptable. It is slightly lacking in mentioning prerequisites or consequences of unclean shutdown, but for a quit tool, the description is adequate.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.