GPT-4 has a lot of problems with recent versions of APIs. Working with Cloudflare workers was initially painful because of the dated code it would generate. The code would be valid, it just didn't work with the initial scaffolding wrangler generated.

I've found copying and pasting chunks of the API context into the prompt solves 99% of it. I'm now able to get it to generate modern workers just fine. You can copy an example method signature, some docs, etc. and it picks up on that fairly reliably. I've even just copy-and-pasted an entire worker implementation (100+ LoC) at the beginning of a prompt and that worked.