How to describe an expected play-json Reads format programmatically

I have many case classes that defines json Read/Write/Format using play-json library. Typical example of such a definition is done using macro

case class Payload(
                    file: FilePayLoad,
                    comment: String
                  )

object Payload {
  implicit val format: Format[Payload] = Json.format[Payload]
}

No trouble for writing more specific formats or anything else using the library apis.

Is there any possibility to perform reflection or type analysis on the OReads implicit defined ? I now little about type level programming, and enough about implicits to retrieve the implicits generated by the macro expansion but I'm working on a self discoverable REST api and I would need to print out the expected JSON format for a given payload case class

Is there any way to reverse the play-json reads definition to print something like this

 "format": {
    "/payload": {
        "/file": {
            "type": "FilePayLoad"
            "format": {
                "/name": {
                    "type": "String",
                    "optional": false
                },
                "/mimeType": {
                    "type": "String",
                    "optional": false
                },
                "/filesize": {
                    "type": "Double",
                    "optional": false
                },
            },
        },
        "/comment": {
            "type": String,
            "optional": false
        }
    }
 }