I'm done with searching all places on the net, but I cannot find a solution to this. I have written the code for Facebook share to share a post on Facebook using the Facebook sharer code. The &u and &t parameters for it are working fine, but I am unable to change the description for the same. The &p[summary] doesn't seem to work. here's my code:
<a rel="nofollow" href="http://www.facebook.com/share.php?s=100&u=<?php echo curPageURL();?>&&t=<?php echo $title;?>&p[summary]=<?php echo $desc;?>" class="fb_share_button" onclick="return fbs_click()" target="_blank" style="text-decoration:none;">Share</a>
From what I can tell Facebook's old sharer.php posting mechanism isn't supported anymore by Facebook. The old documentation link https://developers.facebook.com/docs/share/ auto redirects to https://developers.facebook.com/docs/reference/dialogs/feed/.
You can though use the Facebook debugger: http://developers.facebook.com/tools/debug