You should check your state law or local ordinance. The construction of the pool must satisfy the requirements. There must be fences and child safe locks. The pool cannot be a death trap for children. Before you rent, you will need a professional to inspect the pool.
In the lease, you will need a session to reserve your rights to peridocially inspect the pool to make sure the tenant follows the lease. I would also add an indemnification clause in the lease to release you from any liability that may occur.
You can find someone to maintain the pool or require the tenant to maintain the pool.
Lastly, you may ask the tenant to purchase additional renter insurance police and add you the landlord as an insured in the policy, in case something happens.
You should get an attorney to help you search the law and draft the lease. Even if you did all of the above, there is no guarantee the tenant would not sue you if something happens. You can take it to the bank that if something did happen, the tenant and his or her attorney would always find a way to hold you liable.
