Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the baseline would be 3, but the description goes further by explaining what each `type` value actually returns (code/name/zdf/zxj for stock, multi-pv heat values for wx, news_id/news_title/source for news, symbol for sector, title/tag for etf) and warns that the five field structures are incompatible. That is genuine semantic value beyond the enum list in the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.