A contractor is a person or an organization hired by the client to complete the project. In summary, the roles and responsibilities of contractors have many different levels since they carry out broad range of tasks and manage numerous individuals. Role and Responsibility of Contractor. ontractors are responsible for supplying the necessary equipment, material, labor, and services to complete your project. They hire specialized subcontractors to perform either a portion or all of the work. Contractors use Subcontractor Agreements to protect themselves and the subcontractors they hire. The details include the name of the contract, contract number, name of the user who has created the contract along with the date and time, the status of the contract and the date when the contract is going to expire.