Instead use the Meta description tag. That will help you provide a good description to people when they actually see your website link in serps as it is used to entice more clicks from viewers/buyers.
And you can *Add* kws(keywords) in there for your webpage. Don't overuse your kws in there though.
Bye the way, if your still curious about how many kws to add in the Meta kws tag, you can try looking at your competitors page and get any idea of how they are using their kws for their page. View the source of the page.