Mahav - I sense two possible meanings for "title and description" as you ask the question.
"Title" might mean the page <title> element, which would also be the text that appears in the link on the Google results page, and "description" might refer to the meta description... which Google displays as the snippet in its results. As tedster suggests, these should be unique for each page of your site.
...when you refer to titles and descriptions in backlinks, you may be using terminology that often refers to links from directory listings... where the "title" is the anchor text used in the listing, and the "description" is the text that appears below the title in the listing.
Not all backlinks are from directories, and not all directories have the same listing policies. But, considering directories for the moment... some directories will only provide "titles" or anchor text that's your company name, or domain name, or whatever. Others will use whatever webmasters submit.
When Google evaluates backlinks, it looks for naturally occurring patterns, but also for evidence of some sort of independent editorial policy, either on the part of the directory or the linking site.
Varying anchor text on every link and description is too much variation to be natural. But too little variation would suggest that your backlinks weren't independently given
The same is true for links that aren't in directories... too much repetition suggests an unnatural amount of coordination. On the other hand, Google probably expects some degree of self-promotion, so they might expect some repetition to be natural. It gets tricky, and there is no easy answer.
[edited by: Robert_Charlton at 9:39 am (utc) on May 29, 2009]