thanks for reporting this!
I have created JIRA with this issue, you can track it there: [JBIDE-26990] Hibernate Tools 4.12 not working with Eclipse 4.12 (or 4.13) - Red Hat Issue Tracker
I am afraid that without some more information there is not much that we can do.
What exactly do you mean with 'not working'? Can you either describe in detail and step by step what you are doing to get this null pointer? Also please attach the complete stack trace that you are getting.