Had Gizmodo not changed the login approach, could FB send a DMCA takedown request in good faith to GitHub? I'm asking for a...um...friend that is developing a client-side-only open source tool that allows them to automate tasks on websites they visit from their computer, some of which may require credentials.

Is the law settled with regards to distributing non-commercial tools to do something a site may not allow in their ToS, or is it similar to doing it yourself where it's fuzzy based on the reasonableness of the ToS and intent and a whole bunch of other things?