How do I know if an arrival procedure (STAR) clearance includes altitudes?
In the U.S., the phrase "Descend via the (arrival)" means that you are cleared to the altitudes as published.  Without that phrase, simply cleared for the ___ arrival, then your clearance is the fixes, but ATC will assign your altitude explicitly. In this case, the published altitudes may later be assigned, so descent planning should still be based on making the next fix at its altitude. You just don't go below your assigned altitude until cleared lower.

FAA Explanations:
Starting on page 8 for "descend via" clearances: http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afs/afs400/afs470/pbn/media/rnav1_rnp1_rnav2/climb_descend_via_faq.pdf

More succinctly: https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2014/InFO14003.pdf