How do I update goal approval rule so it triggers only when goal description is updated?

Summary:

How do I update goal approval rule so it triggers only when goal description is updated?

Content (required):

Today goal approval is triggered when all key attributes are updated, can I get the goal approval triggered only when the description of the goal is updated?

I am ok to keep existing approval process when a new goal is created, canceled or deleted. Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):