When working with extensions in Watson Assistant just using the standard UI can be cumbersome to do deep dive analysis on why your extension is not working as expected.
You can use the browsers inspector to look at what is sent and received. You do this by going to the network tab, select “Response” then filter by “callout”. Once you get to the line where callout is mentioned remove the filter and then you can see all the parts.
For the video demo below I created a sample extension that pulls jokes from “I Can Haz Dad Joke” via their API. The sample extension is attached.