Das sagt die FAA

Clearance to “descend via” authorizes pilots to:

1. Descend at pilot's discretion to meet published restrictions and laterally navigate on a STAR.
2. When cleared to a waypoint depicted on a STAR, to descend from a previously assigned altitude at pilot's discretion to the altitude depicted at that waypoint.
3. Once established on the depicted arrival, to descend and to meet all published or assigned altitude and/or speed restrictions.