If you don't have a local node (its highly recommended to have a local node for use of this library), you will need to get the develop version of piston installed, to get the automatic fallback to remote node (new feature in python-steemlib, not on master yet).
Just run this after installing steemtools:
pip install --upgrade --no-deps --force-reinstall git+git://github.com/xeroc/piston@develop
pip install --upgrade --no-deps --force-reinstall git+git://github.com/xeroc/python-steemlib@develop
pip install --upgrade --no-deps --force-reinstall git+git://github.com/xeroc/python-graphenelib@develop