I like TS for the completions and the documentation. I know OP was complaining lack of documentation but knowing what properties a giant object takes, even if those props don't have doc-comments, is still wonderful.

What I've been doing is, whenever I'm handed a random JSON blob, I throw it into a JSON->TS interface converter, paste that back into my project, and I never have to question what the heck the server is returning to me again.