Only one tool you need on a ride- A big hammer.

Not for the bike- for you as you have not maintained the bike well enough.

Apart from tyre repair stuff- I carry a Multitool. No idea what make as I have 3 wedges- one on each bike I ride regularly. You might need an allen key and occasionally a screw driver. Any more than that and it would be a Mobile phone.

And break a chain and you will need a Chain link remover. Break a cable and you may need a cable cutter- Wheel bearings go tight and you need cone spanners---Where do you stop?

Go light and cater for the fact that you are a fantastic mechanic that does all the prep before the ride.