What you carry in your bag is going to change with time. Don't ever think you can adopt someone else's list as your own, and you will never change your mind. That is not how it works.
Crackshot has given you a very thorough list. But, please notice that his list describes in order what he needs to make his gun go " boom ". That is the System of anaylsis that you use in deciding what you carry. If you don't know the system, you are never going to have something you really need, and will carry a lot of stuff you don't need.
When I was shooting percussion, I carried:
1. Ball in a ball bag made of leather, to keep them from rolling around in the bottom of the bag.
2. Cleaning patches in a pocket in the bag;
3. Pre-lubed patches for my gun in a brass round cannister;
4. percussion caps in a separate brass tin;
5. A Capping tool filled with caps.
6. A Nipple Wrench.
7. A Screwdriver.
8. a bottle of moose milk for cleaning the gun nightly.
9. Extra nipple.
10. Ball pulling screw.
11. Patch pulling screw.
12. extra jag.
13. My Adjustable Powder measure.
14. My Short starter. ( soon to be eliminated by coning the muzzle of my gun barrels.)
I carried my powder in a horn separately.
I also carried a knife separately or on the strap of my bag( when I got a new bag.) I always left the cleaning jag on the end of my ramrod, even though it would get black with residue when the gun fired. I used a cleaning patch with a little moose milk if I had time, spit if I didn't, to first wipe off the nipple after firing, and around it. Then the same patch was run down the barrel to pull out the gunk. Then a new patch was run down the barrel to dry it.
Over the years, I began leaving the ball puller, the patch puller, and the extra jag in my range box. Since my capper held upwards of a full 100 caps, I stopped carrying the extra tin of caps.
I don't like the knife on my strap, as I thought I would, and am contemplating sewing a keeper on the back side of my bag to carry both my knife and camp hawk, so I don't have to carry them on my belt. I usually don't carry the hawk when I am hunting.
That is what I mean by evolving choices as you gain more experience. Now that I primarily shoot flint, my new bag contains other things. The secret is not in carrying enough, but in carrying too much. Its hard to pare the list of things you carry in a bag.When my barrel is coned, I will stop carrying that cannister of pre-lubed patches, and simply cut them at the muzzle, and lube them using Dutch Schoultz's dry lube method. I have a ball block, so I am going to probably leave that ball bag in my range box, too. I don't need 20-50 balls in my bag to go deer hunting.