If you have made your own CMS like thing then there's a better idea for you.Do as i say.. In the table of posts insert additional field for META description and Meta keywords. And while you are entering new post Insert these two things in database. And during particular page retrieval call a function which will consists of code to extract meta tags from your database and put it in <meta> tag , so that your meta tags would be dynamic.
And meta tags would be different on different pages.. It helps a bit in search engine optimization though many of the search engines won't only concentrate on meta.. but it surely helps a bit.
You will be having something like
Code:
<meta description='<?php metaextractfun() ?>'>
<meta keywords='<?php metakwdfun() ?> '>
I am half asleep so there might be syntax error in above code but it would be something like this.