If you're limiting yourself to Park brand, then the answer is NONE. If only speaking in general terms, the only must haves are what you need for the work that you actually do. For most "lite duty" mechanics, that's tire levers, a few hex keys and maybe a cassette remover.

I've been manufacturing bike tools and teaching repair for 40+ years and rarely use anything more than a hex key on any sort of regular basis, and a 5mm key is the ONLY tool I carry for anything up to a 200 mile weekend trip.