Hi ,
You can Simply create a WADL file using SOAP UI tool.
Depending on your API if you want to pass request in the body or as the parameter it can be generated using SOAP UI Tool.
Just Create Rest Project and test the API.
After testing the API just right click on the Project and click export WADL.
This is how you can generate a WADL for your API.
Please correct me if I am wrong.
Regards,
Irfan