Meta tag description vs. keywords

The Meta tag description should be English sentence writing.

see the example from 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 &amp; laptops, Appliances, Jewelry,
...Pet Supplies, Invitations &amp; announcements, Gifts &amp; tickets,
Musical Instruments, Costco Business Delivery, Accessories">

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