Meta description code's character number related to 1100.gr web site is seen 170 character. When too many search engines list the result of searching interrogation, It doen't display on listings after 150 characters. To your character number gets over this limit, your explanation will be half. So you can make your explanation in meta description part to suitable for search engines criterias. Also meta description is a explanation part which gives advance information about internet site. If you only add keywords these codes, search engines can decrease your site on searching. For a better quality optimization studying , you can impose the keywords in meta description parts within sensible sentences.