If someone asks you a question online or via text, do not respond with “OK.” or “Yes.” If you use “sure” or “yep” you may want to follow it with an exclamation point, or risk sounding passive-aggressive, dismissive, or angry.
Advice columnist for the New York Times, Caity Weaver, explains that by replying with “O.K.” or “K” you could come off as rude, and instead recommends writing back “kk” or “O.K.!”
Linguist Gretchen McCulloch says the reason is the same reason you’d say “Doctor, could I possibly trouble you to open the window?” versus “Open the window!” in real life.
One way to do so via text is with an exclamation mark. She also suggests paying attention to how you tell people yes in real life and try to emulate that when you’re typing. This could include using “yep!” or “sure thing!”, for example.