Grammarly offer two options ,
free versions and paid versions .the free versions is not useful ,
check the link :https://app.grammarly.com/
I will try others tools ,poor English grammar not accepted by google AdSense
google AdSense roles :
You should be focusing on useful, original, valuable, search engine ranking content rather than minimum numbers. AdSense don’t specify minima or maxima.
Visit this thread in Google Adsense forum.