Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given the tool's simplicity (no parameters, no output schema, no annotations), the description is nearly complete. It states the purpose, the no-op behavior in flattened mode, and the reason for that behavior. The only minor gap is not defining 'domain selection' or 'flattened mode', but these are contextual concepts likely understood from sibling tools and the environment. The description is adequate for an agent to decide whether to invoke this tool.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.