The usual thing you find if you search the web looking for a way to keep Alexa from constantly saying “OK” to your commands, is “Oh, that’s easy: just turn on Brief Mode.”

Thing is, that only works  (ahem)  briefly,  for one or two commands, and then the syrupy “OK” comes back.  What we want is for “brief mode” to stick forever, not for a few hours. This has been driving me, and thousands of others, crazy for years now.

I believe that I have found the solution. It’s not what you’d expect, unless you’re a retired programmer like me.

You DO still need to turn on brief mode, with “Alexa, enable brief mode.”

Then, instead of saying “Alexa, turn on the kitchen lights” (and getting an annoyingly cheerful “OK!”), change what you say to the very bare minimum, which (thinking like a programmer) is:

“Alexa, kitchen lights on.”

Alexa/Device/Command.  AND NOTHING ELSE.

“Alexa, turn on the kitchen lights” is “chatty” and Alexa will respond in kind with a cheery “OK!”  

“Alexa, kitchen lights on.” is the bare minimum command, and there will be no vocalized acknowledgement.

This has worked for me, and Alexa has quit saying “OK” to my great delight.

I hope it works for you, too!