Is 500 words to long for a cover letter?

I'm currently getting my Manuscript professionally edited. I'm starting to sway more toward self publishing and I'm currently doing my due-diligence. However I think I would get great value from at least hearing what an agent has to say. I've prepared a cover letter which is 500 words, is that too long?

The format goes something like this:-

1) I have completed a novel of 100,000 words...

2) The central concept is...

3) The genre is Science Fiction set in....

4) I think my audience is....

5) The story is about...

6) I enclose the first three chapters...

7) About me...

8) I've chosen you as an agent because...