test.cs

public static List<string> GetKeywords(string text, int numKeywords = 10)
{
  // create a list to store the keywords
  List<string> keywords = new List<string>();

  string prompt = $"Create {numKeywords} keywords and synonyms from the following question that can be used to find information in a larger text. Create only 1 word per keyword. Return the keywords in lowercase only. Here is the question: {text}";

  // create a request object
  Request apiRequest = new Request
  {
    Messages = new[]
    {
      new RequestMessage
      {
        Role = "system",
        Content = $"Always provide {numKeywords} keywords that include relevant synonyms of words in the original question."
      },
      new RequestMessage
      {
        Role = "user",
        Content = prompt
      }
    },
    Functions = new[]
    {
      new Function
      {
        Name = "get_keywords",
        Description = "Use this function to give the user a list of keywords.",
        Parameters = new Parameters
        {
          Type = "object",
          Properties = new Properties
          {
            List = new ListProperty
            {
              Type = "array",
              Items = new Items
              {
                Type = "string",
                Description = "A keyword"
              },
              Description = "A list of keywords"

            }
          }
          
        },
        Required = new List<string> { "list" }
      }
    },
    FunctionCall = new FunctionCall
    {
      Name = "get_keywords",
      Arguments = "{'list'}"
    }
  };

  // get the response
  if (GetResponse(apiRequest) is Response response)
  {
    // return the keywords
    return System.Text.Json.JsonSerializer.Deserialize<ListReturnObject>(response.Choices[0].Message.FunctionCall.Arguments).List;
  }

  return null;
}