Hi @solomong,

I don't believe the Attendance/Roll Call tool has an API available.  It's actually an external tool integrated into Canvas, which means and if an API were ever developed for the tool, it would probably be a standalone thing and not directly connected to Canvas.  The  Solved: Attendance Report Using API - Instructure Community discussion has some alternate suggestions that may work for you, depending on what exactly you're trying to do.

Hope this helps!

-Chris