Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given two optional parameters, no output schema, no annotations, and a large sibling set, the description is drastically insufficient. It does not explain the nature of 'items', the output format, when items are 'selected', or how document_id affects results. An agent cannot reliably call this tool correctly from this description alone.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.