This script checks how cohesive your Composer package is, i.e., your file dependency clusters.
If you've got a single cluster, you're all good, your package is very cohesive. If you've got one big cluster and several small ones, you should be fine. If you've got 2 or more larger clusters, you probably want to split your package into several smaller packages.
Inspired by the chapter on modules in Uncle Bob's "Clean Architecture".
php check.php path/to/your/project
No .phar file? No Composer plugin? Just a script?
I just threw this together in a couple of hours. If there's interest, I'll work on it a little more.