Having built a webhook system for our product, I'd caveat that webhooks are "harder than they seem, but not that hard".

The big components we ran into were:

1. Having retry logic if you don't get a 200 back. And some way of flagging the failed requests. We already had a pretty robust job queue/worker setup on our side, so it was a lot easier to add webhooks with that logic in place.

2. Keeping a webhook log. On our side we had a request history already that kept a log of our LLM requests, so it was pretty easy to reuse.

3. Auth / dev experience. Some way for a developer to put in a url + headers + auth method and click "test".