I can only echo the sentiments about "actions" and "knowledge". I was unable to get anything useful out of knowledge documents (apart from the smallest of PDFs

I can only echo the sentiments about "actions" and "knowledge". I was unable to get anything useful out of knowledge documents (apart from the smallest of PDFs). Most times it took ages trying to index the files and 90% it exploded in the end anyways. A few other times it did even seem to kill the entire chat instance, with it erroring on every message after I uploaded a document. Actions provided via an OpenAPI spec are a blast on the other hand. I was surprised by how well it handled even chained action calling (though it lags a bit between individual invocations). It also handled big bulk listing endpoints quite well. If you already are generating OpenAPI schemas for your API, you are basically getting a very customized GPT for free!