Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given a tool with 2 parameters, 0% schema coverage, no annotations, no output schema, and multiple sibling tools in the same domain, the description is completely inadequate. It provides no information about what the tool returns, how to use its parameters, when to choose it over alternatives, or any behavioral characteristics. This leaves the agent with insufficient information to use the tool effectively.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.