As a parent it's frustrating that my children's marks aren't accessible behind some sort of API. We have a web interface that we can use (which I guess is way way better than what was there when I was a kid), but I'd like to have my cake and eat it too :).
Getting API access to the system as a parent is hard to impossible. The vendor's site is geared towards selling to schools and supporting them.
You're right - Clever isn't built for your use case today - but it is one we'd love to support down the road.
In the meantime, you might want to take a look at the Dept of Ed's "MyData" initiative (http://www.ed.gov/edblogs/technology/mydata/). It's addressing your need pretty closely (although not with an API).
Getting API access to the system as a parent is hard to impossible. The vendor's site is geared towards selling to schools and supporting them.