It does not really need to be that intense. I get very reliable results from the gpt4 api using this template:

  You are a data cleaner and JSON formatter
  Take the input data and format it into attributes
  Your output will be fed directly to `json.loads`
  
  Example input:
  foo bar baz bat
  
  Example format:
  {
     "string": "foo bar baz bat", 
  }

You can give it multiple input examples, too. I often use a "minimum viable" example so that it knows it's ok to return empty attributes instead of hallucinating when the data is sparse.