The Meta Description tag generally has a short summary of what the visitor might expect to see on the landing page. It is placed inside the <head> section of your HTML page but there can be situations where you’ll be better off not using the META DESC tag at all. Stoney writes:
You don’t always want or need a description tag on every page. There are some instances when you would be better served not having a description at all. For me, the general rule is if you’re targeting broader keywords, use the description tag. If you’re targeting long-tail keywords then don’t.
The reasoning here is that if you’re going after long-tail phrases on an article page or blog post, then there are simply too many variations to attempt to work them into a 40-word description. On the other hand, if those long-tail words are in the content, without the description tag, the search engine will import snippets from the page based on the search. This increases your likelihood of getting actual keywords into the description content below the clickable link in the search results. link.