I have created a project for easily writing this type of test with YAML:

https://github.com/hitchdev/hitchstory

I dont think that this type of task is really appropriate for an LLM though. It is better to use hard, prewritten abstractions for the truly deterministic stuff (e.g. click).

For other situations where you may need to do subtle trade offs (e.g. choosing an HTML selector for the search bar) an LLM will generally do a bad job.