Whenever practical, the department may execute a contract with a person qualified to provide assistance services under this subchapter, if the contract for the assistance services is cost-effective and the quality of the services ensures compliance with state and any applicable federal law. A person executing a contract with the department for the purpose of providing the assistance services shall be deemed to be a depositary of the state and an agent of the department only for purposes expressly provided in this subchapter. The department shall periodically review assistance services performed by a person under the contract to ensure that quality, cost-effective service is being provided.