Google updated its documentation on creating best meta descriptions that will show on the search results Page. This change was made for for controlling the snippet in the search results.
Snippets are mainly created from page content automatically. Snippets are designed to answers the best relates to a user's specific search
Google sometimes uses <meta> tag content to make snippets, if they think they give a more accurate description to user compare than can be taken directly from the page content
Don't Add only Keywords.
Too Short Meta Description
Doesn’t summarize the page
Same description is used in every news article
Describe Your Business, Not the Webpage.
Be specific and detailed
Summarize your page content
Use webpage content