The Meta tag description should be English sentence writing.

see the example from Costco.com

This is the keyword setting for Costco.com

<meta name=”keywords” content=”Shop at Costco, Costco Canada, Great, deals at Costco, Low price, Music, DVDs, Baby, Health, Personal Care,Beauty, Electronics, Computers & laptops, Appliances, Jewelry,Pet Supplies, Invitations & announcements, Gifts & tickets, Musical Instruments, Costco Business Delivery, Accessories”>

This is the description setting for Costco.com

<meta name=”description” content=”Costco Wholesale operates an international chain of membership warehouses, carrying brand name merchandise at substantially lower prices than typical retail.”>