Isn't that supposed to come with the tractor? A nice little common tool kit for them is supposed to be in the tool box I have bee told by one dealer. Mine had the allen wrench but nothing else. I looked in a bunch of other new tractors on the lot yesterday and all their boxes were empty.
things I recommend carrying is that 12 MM
10 mm combination wrench. (bleed screws)
13 mm combination wrench (for switching your spool valve int eh back from single acting to double acting)
15 mm combination wrench (loose banjo fittings)
17 mm combination wrench (injectors)
flat heat screwdriver both small and large ones.