/dev/input/mice
That rounds up all the usb input mice/tablets.
Of course, you also realize Debian does not allow a "succeed" anyway when it comes to mice and keyboard with mice not found.
There is a stanza entry that you can use to work even it the mouse pointer fails... it escapes me right now. I use it for being able to have a headless machine with X and do XDMCP logins to a machine like that.