Debugging robots made in Google Wave can be a little difficult because it can only be tested on the server and it can be difficult to see how it is sent.
A way I have found is quite useful is to use the app engine log. On the log tab select “Requests only” and then see that data being sent to the robot. It is this data the robot can see, if it is not here then the robot API is not receiving the data.
I hope this help you debug and get at better understanding of your robot.
Update 19 aug 2009: If you want to format the JSON try the JSON formatter.