You've gotten a bunch of good info here, from many who have been there and done that..
I also found I had to enrich my tool set when i got a tractor. I had the usual 1/2 socket stuff and wrenches.. I ended up getting quite a few tools from discount parts houses. Most of these tools were necescarry.. but only used once... I believe harbor freight has decent prices.. and if you are only gonna use something once.. might as well not pay twice what its worth.. though.. there are some things you want to be good quality.
I carry a pair of pliers w/ wire cutters, some bailing wire, a few extra lynch and hitch pins, and an adjustable wrench in my tractor tool box.. ( the old 8n also has an extra spark plug cable)
Soundguy