By external tool I suppose it is about "New quizzes" in Canvas. It depends on the settings in the quiz. When you create a quiz, you can set it so that people only get points if they choose the right answers, that is, you get zero points if you choose too many or too few (Exact match). A multiple answer question can also be set to "Partial credit with penalty". It means that if you have a three-point question with three correct answers and you only choose two correct answers - you get one point.
