I wrote up some internal guidelines about how we look into and evaluate health & quality of #RustLang crates at Embark:

https://gist.github.com/repi/d98bf9c202ec567fd67ef9e31152f43f

these are not exact rules but things to consider, esp. for adding dependencies for long term use in large Rust project in production.

our project is ~500k LoC and uses ~700 crates, so some care and active gardening is in needed. which is why we (read: @ca1ne) also built cargo-deny and cargo-about early on and use it heavily.