The text that you've suggested in your question is very similar to what you should write.
In US business writing, it's important to get straight to the point. Other than greeting and signing off, you don't have to engage in formalities. If you come from a culturecountry, such as France, that valuesuses traditional formalitiesstock phrases in official correspondence, or cultures that value indirectness, writing this way can feel uncomfortable. The text that you've suggested in your question is very similar to what you should write.
You might also feel uncomfortable about other issues related to the subject material. For example, you might have concerns you have about the employee's performance. If you can't express those issues quickly and easily in writing, ask for a "follow-up meeting to discuss the job description and some related concerns that you have"concerns" in person.
If your work requires you to write a lot of business correspondence, there areyou can use books that provide templates and guidelines that you can followexample letters. These are useful but limited in scope. I likeprefer The Big Book Of How To Say It (How To Say It And How To Say It At Work) by Rosalie Maggio. In that book, but there are many othersthe author helps you write more authentic correspondence by suggesting some key phrases and providing guidelines to follow.