Yea exactly. The LLMs are tuned to natural language. I don't think anything will beat good ol' templating (a.k.a. plain text). In Go I do something like this:

  // mytemplate.tmpl
  Description="The following data is for the users in our application."
  Format="id,name,role"
  length=2
  Data:
  {{range .}}
  {{.ID}}, {{.Name}}, {{.Role}}
  {{end}}

This way you're able to change the formatting to something the LLM understands for each struct. The LLM might understand some structs better as JSON, others as YAML, and others in an arbitrary format. Templating gives you the most flexibility to choose which one will work best.