What did I miss? What's the best answer you've ever heard? How do you evaluate 3rd party dependencies?
Of course there can be libraries that are more or less "finished", so the last commit/frequency of commits isn't on its own a deciding factor, but in proper context/holistically it is definitely an important metric!
Contributors is the most informative page for me. So many projects are 1 man show basically all the time. I don't mind that, it means passion, but it also mean it can dissaper any moment depending on circumstances.
I also look into issue details to see how maintainers communicate with community members that do due dilligence before aksing for help.
Stars only mean something because of the people who do. They're the ones leading the herd. If you're just going off the social signals, then you're just monitoring where the herd is going.
The main question I'm asking myself while looking at the code is: if I had to fork this thing and maintain it myself, how would I feel about it? Because sometimes that happens.
I actually blogged my answer to that exact question recently (shameless plug):
(When I was in high school, I used to work for a pre-Internet company that helped people pre-filter interview candidates for ads posted in classified sections of newspapers and what they did was have questions like this that could be asked by people well before they reached your calendar for an interview.)
If you avoid building on something that's constantly shifting (the web) then the need to update goes down significantly.