Why not use the UNIX idea of composability and relegate all the JSON construction to another tool, e.g `jo`: $ jo query="six times nine" answer=42 | curl -

Why not use the UNIX idea of composability and relegate all the JSON construction to another tool, e.g `jo`: $ jo query="six times nine" answer=42 | curl --json - Sending JSON... {"query":"six times nine","answer":42}