I'm kind of worried it will install extra dependencies on my system. Will it?

Depends what you mean - Pants will download things like Pytest and your 3rd party dependencies so that it can run these tools, but that happens in

~/.cache/pants

and won't leak into your system If you install Pants via the

./pants

script, pip will also install Pants dependencies into

~/.cache/pants/setup

. If you use the Pex approach, that part is skipped