I’ve just put together a very basic tool kit for my scrambler 1200, puncture kit, tie raps, rubber gloves ,fuses,Allen & torx & screw driver heads,8,10 mm spanner’s, the 10 mm spanner I use with 10 mm Allen socket to undo the oil filler cap, when your away touring you may need to add some oil and you be fxxked if you couldn’t get the cap off.i also keep spare batteries for the fob under the seat and two batteries for the fob are all you could fit under the seat.
off eBay bob it was £25ish , it was advertised under leather Bicycle tool bag, the seller was Londoncraftwork,mines real leather but some aren’t so if you want real leather check before you buy, it’s ideal size not too big or small.