How to add description for each api response data in swagger api doc

Hi, I am creating api using Swagger. My api is working fine. Now what I want is, I want to add description for each data that is returning my api. Suppose here is my api functionality.

@SWG\POST(
        path="/api/data",
        tags={"datas"},
        summary="returns all datas",
        description="Base url  is : http://example.com/",
        @SWG\Parameter(
            name="Authorization",
            in="header",
            description="Token to access Audio File",
            required=true,
            type="string",
            default="Bearer TOKEN",
            description="Authorization"
        ),
        @SWG\Response(
            response="200",
            description="Successful operation",
        ),
        @SWG\Response(
            response=400,
            description="Invalid Data| Data not in request"
        ),
        @SWG\Response(
            response=401,
            description="Invalid token | Header Token is missing"
        ),
    )

This api functionlity returning data like this : 

{
  "data": [
    {
      "id": 1,
      "title": "Title of the file",
      "description": "description of file",
      "content": "content name will be here",
      "thumbnail": "content thumbnail will be here"
    }
  ]
}

Now what I want is, I want to add description in the documentation what does id, title, description, content & thumbnail means?  I simple word I want to add little description for those. I have tried adding $ref and  describing responses. But it is not working. Almost every time I am getting error like this failed to parse JSON/YAML response. Please help me on this. Thanks