Android Lint - What to do with it?

I have installed an add-on (Lab Lab Class Diagram Editor) from Eclipse MarketPlace.
Since then I have been getting errors about Android Lint when eclipse starts:

Android Lint has encountered a problem.
Failed
java.lang.NullPointerException

      

        
        
        
      

    

...

Android Lint has encountered a problem.
An internal error occurred during: "Running Android Lint".
com/android/ide/common/sdk/SdkVersionInfo

      

        
        
        
      

    

Then Lint stops working and I can't access the window -> Launch Android Lint -> ...
I've never used this on purpose, some people say without it. It seems useful though, and I would prefer it to work.

Not the first time I have problems with Lint, every time you change your environment a little, Android ADT seems to have problems. I'm still new to Eclipse / Android ADT and I may have used it incorrectly.

What is Android lint?
The Android lint tool is a static code analysis tool that checks the source files of an Android project for possible errors and optimization improvements for correctness, security, performance, usability, accessibility, and internationalization.
from http://developer.android.com/tools/help/lint.html

Is Android Lint useful? Does it normally crash so often when you install add-ons or modify your environment? What's a good practice for it to work?