How do you tell your kids that you are too tired from work and you won't be able to play or attend to them as you need to rest first?

I think if you cautiously word your concerns, and put it delicately, they'll understand that you work hard and need to get some rest before playing or spending time. Obviously, you're going to be experiencing similar encounters down the road, so I wouldn't personally condone making it up to them each and every time sine that sets expectations. Maybe try to instill a nap time into all of your schedules, so everyone is rested and 100% when it's time to spend time and play