Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
With no output schema, the description usefully lists the returned meeting attributes (date, time, timezone, duration, GMT start/end, facility), which is the right compensation. It still leaves out pagination, empty-result behavior, and error conditions for a two-required-parameter lookup.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.