I love this multi-tool look. If only it wasn't a C class...

No, procedurally generated - this means that the vast majority of what's in the game is persistent, though what you find in which locations is essentially random in nature.

With regard to multi-tools, there is only a small handful of models in each star system, maybe 4-6ish? Maybe less.

The places from which you can purchase multi-tools are consistent in the class of MT they sell. If you find one selling an S class, there is a decent chance it will be the one you want. If it's not, you can "trick" the game into spawning a different model by... ok my memory is a little vague here... I think, by doing a manual save (interact with the outpost location pole thingy outside) then quitting and reloading, and checking the vendor again - you'll find a different model from the star system weapon pool, but since you're at the same vendor, it will still be S class.

This step only works once though - once you have got it spawning the second model, it will stay as that model if you just repeat the previous save reload process.

But despair not! If that doesn't work, the next step is to fly off and land on another planet in the same system (place a beacon at the S class vendor first!), manual save on that planet, quit, reload, then fly back to the S vendor again. You should see yet another model from the same system, but again in S class. Repeat until you get the MT of your dreams!

Obviously this is super grindy at the start, checking outpost after outpost before finally finding one that sells S, but if you know how to exploit the cartographer it should make a bit easier. Upgraded scanner modules in exocraft might be a good way to go as well.

Again, my memory of this is a little vague, I may not have the details exactly right, but the process is definitely something very close to this. If you're super keen, do some googling or ask in this subreddit, someone will surely confirm the correct process pretty quickly.

Oh and by the way, I should mention specifically that this principle work for the MT vendor on space stations as well - if you happen to find a space station MT vendor selling something S class, but not something that you like, you can do the same land on a planet, hard save, reload, revisit the vendor trick to force it to spawn different models from the system pool, but they will always be S class.