I've seen long phrases in keywords tags. four words can be fine! The trick is to not repeat words *within* the phrases more then four or five times- as I understand it.
__________________
...when the going gets tough- the
tough get llamas
I think your keywords should dislpay the content of your site as full as possible. So, it it's a problem: "how to descript your site best of all with the minimum of words..."
Try this website. It is what I use because it has the large search engines on there. It will tell you what is good and what is not about your meta tags.
