As long as its on the tractor before its stolen! Reading the link, it seems to have a short range, <100' to nearest smartphone with the compatible app.
Anything better than nothing, but this device seems better suited to small items around the home, keys, wallet, etc.
Not unless the theif drives it around in small circles around your house.
If you want the ability to track something like that, it's going to cost you a bit more, and it's going to be a monthly charge, unless you are geek enough to rig something up yourself.
Go to something like etrailer.com and look at their GPS trackers designed for trailers. You just mount a little black box on your tractor, nobody in a hurry would realize what is for.