I didn't but fortunately one of my riding buddies had one when my chain link separated after I installed a new chain. I honestly don't remember if I had driven the pin out and re-installed the pin improperly or if the new chain separated due to defect. Regardless, I needed a chain tool and my buddy had one. Now I carry a Park tool in my saddle bags for my vintage bikes and I have a Specialized Top Cap Chain Tool for my modern bike. The Top Cap Chain Tool replaces the steerer top cap and only weighs 25g. Carrying the tool gives me peace of mind when I'm out riding solo.
This replaces the top cap on modern bikes.