Here are a few links to sites with job descriptions for a worship leader.
Use care in crafting your job description. You want to set a framework that will work for the person you are interviewing while understanding that personal growth levels in some individuals may be different at various times.
I am a big proponent of sharing the job description as soon as possible with your candidates. Your expectations should never be a surprise 3 months into the job. That also means you should keep to the job description and not do "add-ons" throughout the year that were not discussed in advance of the position offer.
There are countless more on line that you can review and modify for your church needs.