Dogtrousers
Lefty tighty. Get it righty.
The tools i need to keep me on the road take up very little room. My allen keys, tyre levers, chain tool and puncture patches fit in a neoprene case intended for a compact digital camera. I keep it in a small saddle bag but it will wedge under my saddle or sit nicely in a pocket. Would the OP see my tools if i didn't have the saddle bag? I very much doubt it.
Another option is a tool bottle. A friend if mine uses one. You can fit quite an extensive kit in there and it wouldn't be obvious to a casual observer that you were carrying anything.
Obviously not ideal for long rides in hot conditions with no access to shops as it restricts you to one bottle.
at least that was my idea when I bought one of those tool bottles, but genuinely I find I can fit more in a just an average sized saddle bag than the tool bottle, because the bag expands and I can just shove bits in no problem, even used it to store gels once, whereas the bottle is always width constrained anyway, but unless you can vacumn pack it, you struggle to fit more than a spare tube and a couple of tyre levers in