To use the Polylith tool and to get access to all the features in tools.deps, make sure you have CLI tools and git installed. If you install git for the first time, don't forget to set the user name and email.
To install the poly command on Mac, execute:
brew install polyfy/polylith/poly
If you get the error "openjdk-13.0.2.jdk could not be opened...", do this:
Open MacOS "System Preferences > Security & Privacy > General".
Click Allow at the bottom for "openjdk-13.0.2.jdk".