> managing to produce ergonomic APIs (semi-)automatically [...] I have most experience with the Python library (boto3)

This almost sounds tongue-in-cheek: the slightest use of boto3 makes it seem obviously auto-generated.

It's fine, it even has advantages (whole classes of bugs removed, or at least fixed once fixed everywhere), I just wouldn't call it ergonomic or idiomatic.

's3 = boto3.client("s3")'.