Hi Snowmanz,
1. Create a funtion that grabs text that you wanna use as description.
2. in function create(&$uri) call the function like this:
$this->metadesc = $this->getYourDesc($id);
3. At last use this $newUri:
$meta['metadesc'] = $this->metadesc;
$newUri = JoomSEF::_sefGetLocation($uri, $title, @$task, null, null, @$lang, $nonSefVars, $ignoreVars, $meta);
Best Regards