When you create a library, the CLI puts a path in your tsconfig.json. You can look this up. the name you can use for your import should be in there. (if you did export it properly, it might be that you need to do a so-called "deep import" (`tools/something/else/my-thing`))
And no, I'm not aware of a way to guard against package name collisions. Just make sure you don't conflict.
For myself, I usually use a prefix. (for my Angular things its usually '@se-ng'