API methods

I wanted to make a little webapp, but i wonder what methods r actually available. I wanted to automate the updating of pictures so it inherits description and tags and submits the request to merge.
 
Is this even available?

You can’t upload because Rails will not decode the image parameter as a file, and there is no correct decoding in a non-multipart form.
 
EDIT: updating via API is perfectly possible, however some methods require cookies