Improved Version 1.3
Can't live with them (because they wear a hole in your pocket and look insidious with their threatening bulge-like manifestation in your pocket), and of course, you can't live without them. Solution: use an S-hook to suspend your pocket tool inside your pocket! Comfy, safe, and very stealth. Currently I carry a medium-sized pocket tool -- a Leatherman Juice Cs4 -- but I've had bulkier Victorinox Swiss Army Knifes that benefit just as much from suspension.
Years ago I learned to hang my pocket tools from the inside corner of my pocket, because otherwise they would grind away against my leg if I just dropped them in the pocket, and they would look rather goofy, worse than even an engineer's pocket protector bulge. Also, they are rather expensive items to loose through a developing hole in your pocket -- scenario: you are running for the subway and the tool finally plunges through the hole in your pocket and clatters down to the electrified rails as you step aboard, and the railway security people hold you back from recovering your beloved tool. You must bow pay $1,000 to get out of jail and ~$85 for a new pocket tool. All this could have been avoided with a ~$0.50 S-hook.
Yes, the hook was the thing for me, and all of my pocket tools have gotten them (I am a connoiseur of pocket tools and have a few to suit my changing moods). S-hooks -- oh glorious S-hooks, so useful for many things! -- have kept my pocket tools safe, unobtrusive, and accessible (in fact once I capsized my dory and 360'd it a few times, and had to cut the rigging to get the sail down since everything had jammed, and there my knife was, still hanging from its hook in my pocket. If you want to be really top-shelf, buy a stainless steel S-hook from a marine store to match your stainless steel tool (this will also prevent any galvanic action between hook and tool. Ha! I just told a nerd joke! Did you get it? Huh?).
The useful introduction stuff ends here. You may proceed to step 1, although as ever I have more to say in my appendix below.
The only time I remember being separated from my pocket tool (except for airline trips, lately) was when I had a stroke a few years ago. I was caught by surprise, healthy (well, so I thought), well exercised, relatively young. So, as the ambulance people carry me out on the gurney, I reach for my Swiss army knife on the side table -- perhaps I am thinking they will bring too some of the wood that is in my bedroom with which I am building my outrigger canoe (see instructable 'Build a sailboat-in-a-closet') along with the spare underwear and a book, and I can continue to work on the boat in the ICU with the little saw? I don't know, for my girlfriend tells me I was speaking in Klingon, and so who knows what my brain was thinking?
But I did want that knife. It was my constant companion, my talisman; it has a saw, and scissors, and little pliers, and a teeny drill -- everything needed to fix whatever, though there is a lot in my life right then beyond the heal-all of a pocket tool.
The ambulance people don't know; they gently push my reaching arm back onto my chest, and talk about me like I'm not there. 'What does he want?' they are saying (but not to me, I don't exist). I want my pocket tool, and I don't have it NOT because it has no hook, but because I have no pants on; you see, I had my stroke in the early morning! You can't think of everything.... but don't let that stop you from trying the hook.
Step 1: The Stuff and the Result
(1) A pocket tool. Selecting this deserves a whole instructable, or at least a step, but not today. But this is important: your pocket tool should have a stout key-chain hanger thingie on it. The older Swiss Army Knives did not, and the thin hanger on the knife I owned since 1980 actually came near to wearing through. A Victorinox store fixed my broken scissors spring for free recently but can do nothing about the keychain hanger. Tip: string 1/8 inch nylon cord through the cork-screw and tie the S-hook on it. Good news: Newer Swiss Army Knives now have very thick hangers, and the Leatherman brands do too (at least mine does).
(2) A hook. I suggest an S-hook, the smallest and thickest one you can find, thick because it spread the strain through your pocket cloth better.
(3) A small spring-ring for key-chains (one might come with your tool, but I got mine off retired key-chain Maglites flashlights.
Alternative: I have used picture-hanging hooks (basically, folded flat metal) and though they do work, their edges are sharp and seem to wear the cloth on your pocket more than a small S-hook.
(1) Put the the ring on the keychain thingie on your pocket tool.
(2) Put the S-hook on the ring (the ring-plus-hook permit sufficient twistability so that the pocket tool has some room to move, reducing strain on all the parts). Leave one side of the S-hook open to hook on your pants pocket, though you can close it a little.
(3) Put it in your pocket and start your day ready to face anything that can be faced with a pocket tool! It will feel so comfortable you will have to pat your pocket to make sure it is there. The public will hardly notice it until you go through one of the many detectors that are there to both protect and remove your personal freedoms; see brief rant below:
Brief rant: USA has gone crazy with worrying about pocket-tools; it is very sad; you are now some kind of suspect if anyone sees you with a pocket tool (and if it is a traditional old pocket knife with just a blade or two, then, even worse! Oh, horrors! A knife! A pure knife!).
Warning: It is still possible for the tool to fall out of your pocket when you recline on a couch; I wear loose comfy pants with vertical pocket slits, and that has happened; also while sitting on a car seat, uncommonly. I assume that tight uncomfortable bluejeans with their small, tight, nearly useless pockets would solve that problem, but then you are stuck with uncomfortable bluejeans, which seem to be made solely to look good in advertising pictures.
But in other walks of life, it will be safe -- most recently I've biked, camped, and hiked in Ireland -- very active castle-climbing, rath-exploring, tent setting-upping, and pint-drinking, and I never lost it.
The photo shows me in my weekend workshop pants, with tool efficiently located for low-profile but accessible for the fast-draw. Carry on!