Having the right meta keywords is no longer the key to SEO success. As search engine ranking techniques have grown more complex, meta keywords have taken on less importance in good SEO. On the contrary, it is still important that they be used wisely and effectively. Though more than 30 meta keywords are allowed, best practices narrow it down to five to eight keywords per page, choosing the most relevant to the content on the page. Google has published documents stating that its algorithm does not factor in meta keywords when determining listing positions, but every inch counts!
Also the debate of effort vs. reward: descriptive tags. But creating meta descriptions along with all meta data is imperative to SEO. Though search engines may disregard meta tags in their search algorithms, there is no penalty for optimizing tags. And evidence show that Google publishes meta description content in the actual search results on the display page.