Matt Cutts: ‘Not necessary for every page to have a meta description’
I’ve done a few meta tags in my time and I’m glad this has come up. I even created a specific way you’d be able to identify and make meta description updates to your site using Screaming Frog.
In this video Matt Cutts has stated that he, even on his blog, doesn’t create meta description for all of his pages/posts. Instead he recommends allowing Google to automatically create a meta description by scraping data that is available on-page. However states that for the high ROI pages (or what I call “landing pages”) should have custom meta descriptions.
The only warning that Google’s Head of Search Spam did give is the fact that you should not duplicate your meta descriptions. I would go ahead and say that you shouldn’t really duplicate anything. Whilst this was already known, there are in fact plugins for WordPress that do a much better job at automatically creating meta descriptions than Google.
These are my two picks: