They are tools only in the broadest use of the term that applies to most everything we use to interact with the world. From philosophies like science to the mundane like a spoon. Why use such a general term when a more specific, much more meaningful term is available.

"Medium" is a much more general term than "tool," the edit you suggested adds nothing to anyone's understanding of gp's point, and to suggest they actually 'meant' something that means the same thing is... strange.

Also, they are tools in a much more narrow sense as well, but that is left as an exercise.