I carry the factory BMW tool set, supplemented with -
Folding feeler gauge
Mini-mag light with a 'mouth bit' on it
Spare set of plugs
That's about all that will fit with the lid still closing on it. I carry more tools in my panniers tho (metric ratchet, little 'slime' air pump, tire repair stuff, stack o' skin mags, etc.).
1964 LI125S with a 240 MRB kit