You just need to make the summary memorable. Stock characters are a good way to go, they're easy to remember and identify with, but word it wrong and you can make it sound cliche. For me, to make a good summary, you need to give away a small detail that the readers will find out quickly, and make it interesting. One of the best summaries I've seen came from one of my friends for her Sailor Moon fanfic:

'Dane's not fussed she's suddenly the stormheeled warrior, Sailor Aello. she's got more important stuff to be concerned about then wangsting over a past life. That chainsaw inspired youma rushing at her head for example...'

From that, we know it's set in the Sailor Senshi Universe, the character, unlike most, isn't thrilled to be one of the Sailor Scouts, and makes it funny. That instantly caught my attention (Even though I don't follow Sailor Moon) and made me have a look-see.
Now, let's take a look at 'Opportunity'.

'A young king, having just taken back his family's crown, seeks advice from a loyal duke. How the heck do you rule a whole kingdom, anyway? Same world as "Turn, Turn, Turn" and "Fugitive;" different time and place. Completed May, 2008.'

Ok, we can tell it's slightly unusual, because the King doesn't know what to do. However, what throws people off is the latter part of it. Most, if they follow your stories, would assume it's set in the same Universe, and usually they don't really care when it's completed. I know that does sound harsh, but if you saw that on a story, you'd probably pass over it.
Now, let's see if we can pump some life into it!

'Oliver, having just come to the throne of his Kingdom has come to an epic conclusion; he has no idea how to be king! Deciding to better himself, he seeks out the advice of one of his most trusted subjects to find what it truly means to be King.'

Though it might be me being biased, that one seems a little more energetic. It seems a little lighter than what you might be going for though, so I'll try again.

'With his enemies defeated and his family restored to the throne, King Oliver must try to understand what it is to be a King. Realising he can't take this journey alone, he seeks the help of one of his family's most trusted Advisors.'

It's more stoic than the last, but it gets the information across. The word 'Journey' also peaks the responder's interest, and may make them more likely to click.
But yeah, that's just what's happened with me. Hopefully this helped!