It is HIGHLY recommended that you have a mission and vision statement for your worship team.
Your mission and vision statement for the church may be slightly different than the one used for the worship team, but they should align and focus on the same core items.
Having a worship team mission and vision statement helps in your communication to new worship leaders and sets the tone for any candidates whether home grown or external. It also shows that you value what the worship team does more than just opening the service.
Examples of different mission statements can be found doing a simple search on the web, but here are a couple of examples of a recent search I did.
Once you have a mission and vision statement in place, that should be one of the first things you share with candidates for the role. Can they support the mission and vision? Be careful not to overload the mission and vision statement to make it a full time job just maintaining the mission statement and leaving little time to actually be a worship leader.
GREAT EXAMPLE!
One of the best outlines of expectations for a worship team leader, musician or tech team is on the Gateway Church website.