How can I debug the JSON API?

I'm trying to have a bot call my REST API. Is there a log or some way to debug why the bot always just shows the error message i have set for the bot's failure message?

I have fiddler on my server and the incoming request and outgoing JSON, looks right.

Do you HAVE to have CARDS in the response? I was hoping to ignore that complexity. If it is required it might be my problem.

Also I'm returning back bot_id, user_id, incoming_message and etc back to the bot. The example had those returned.

Here is my response:

HTTP/1.1 200 OK
Cache-Control: no-cache
Pragma: no-cache
Content-Type: application/json; charset=utf-8
Expires: -1
Vary: Accept-Encoding
Server: Microsoft-IIS/8.0
X-AspNet-Version: 4.0.30319
X-Powered-By: ASP.NET
Date: Sat, 11 Aug 2018 21:51:46 GMT
Content-Length: 204

{"bot_id":"25151","user_id":"webchat.1534024295168.testing","module_id":"357605","channel":"testing","incoming_message":"api","message":"blah","suggested_replies":"mysuggestedreply","blocked_input":false}