Pockets are relatively empty tbh, but I've got a small range bag full of spare nozzles, hop up chambers, hop up buckings, and other misc parts for both my GBBR's and back up AEG in my car. There's also a small tool kit full of everything I need to take my guns/gear boxes apart if need be and lots of grease, lube and cleaning supplies. I really can't remember what else is in there but I know I've got a set of small files, spare bb loaders, bb's, bug spray, sun screen, tape (electrical tape, teflon tape, duct tape, etc), unjamming rod, loctite, batteries, anti fog, small FA kit, spare gloves, and socks lol.
On person, on the field... short of my gun & kit, I've only really got a knife, flash light, rag/cloth for wiping stuff (doubles as dead rag), batteries for rds & headset, maybe a bottle of water in my dump pouch, and occasionally a pocket FA kit stowed somewhere. OH and
SNACKS! 
Usually if you need something on the field, I find its most likely a situation where you need to walk off the field anyways so there's really no point in carrying too much stuff on person. That being said... I definitely over pack, but I like to be able to have everything I need to tear my guns apart and maintain them once I'm off the field and back at the parking lot if need be.