Hi @newsasviyauser! You can find the documentation for the MAS REST APIs here. and the execute step is the one that calls the deployed model (or decision).     Yes, you can write your own models as long as they are properly formatted and meet the publishing requirements. For example, a Python model's score code must be defined in the following manner.  I tried to be general in my example payload, but some folks have mentioned it was confusing. So to have a more tangible example, if I had a variable named cost with a value of 10 and another variable named color with a value of blue, the payload would look like the following:  payload = '{"inputs": [("name": "cost", "value": 10), ("name": "color", "value": "blue")]}' "name" and "value" are the parts of the payload that remain the same. And when the variable is numeric, then we don't need to place quotes around the numeric value.   I hope that helps! ... View more