[Plugin: WordPress SEO by Yoast] Page title in meta description, how?

I’ve been looking for days now and I’m more to feel like there is no answer to my need.
I want to add, as a tag, the name of the page within the meta description.
Is it possible?
If I add %%title%% in the meta description field then it still returns %%title%% and not the real title.
I’ve been so desperate to try with php:
<?php echo get_the_title(); ?>
but as I supposed I had no luck with it.

I’ve been searching online for an answer with no luck at all…

Thanks for all your help.

http://wordpress.org/extend/plugins/wordpress-seo/