A multi tool is an absolute must when riding trails and it's very important that you have a chain breaker on it as well.

Let me tell you why, some years ago I was riding with my son in the Barrington Tops and we were leaving the Junction Pools when I had a mishap and bent my rear derailleur.

OK, I thought, no problem I'll just bend it back. All went well until it was nearly straight again when the hanger, simply broke in half!

If I would have had a chain breaker and a chain quick link, I could have removed my derailleur and set it onto a single gear. But I didn't have one so I had to take the chain off the cogs and tie the derailleur to the frame, lower my seat and use my feet on the ground to propel myself! Let me tell you not very compfy and very slow unless going downhill.