I'm often asked for ad-hoc queries that ES answers really quickly, but I end up needing to do some kind of transform on the documents or aggs. I do this with jq, and if its a one time deal often just by pasting the output json into https://jqplay.org/ and writing the tranform there.
It would be great if devtools provided a way to enter a transformation for the query response directly. Maybe by extending the query definition syntax with a pipe operator.
e.g say I just need a list of id's from an index
GET /my-index-2017-01-01/_search
{
_source: "",
size: 1000,
query: { ... }
} | .hits.hits[]._id