Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the baseline is 3. The description adds interpretive value by explaining the meaning of 'possible' vs 'proportional', emphasizing the provenance-model caveat, and noting that truncation is explicitly reported for 'all'. While some details repeat schema text, the caveats and model-choice semantics are not fully captured in schema descriptions, justifying a 4.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.