I still can't read "tool for agile planning" without crying inside my head. We really need "tools" to "implement" "processes" in the spirit of a 6-line manifesto, do we? Sigh.
Aww. Don't cry. It's not a process tool. It's a prioritized to-do list that can track your velocity. Despite being opinionated, it doesn't enforce a process. Though you'll find that if you don't embrace those 6 lines, you'll quickly make a mess inside Pivotal and it will happily let you do so.