Question: On-Page SEO Tool

Is there such a tool that applies your keyword or insert your keyword automatically on your non-optimized article?

I am doing this manually right now.(adding keyword to title, header, body)

Not as far as I know.

Tools like SurferSEO gives you pointers on what keywords and how many of them you need to add to your articles but I don´t know any tool that does this automatically for you.

And, truth be told, I don´t know if I want a tool like that to become available on the market.

depending on the platform there are various modules. I saw couple on Wordpress and Opencart. Most probably there are some on others

Still they take your existing info and don't come up with new words. No AI here, just intelligent scripts