In this work, we propose a model for applying contracts in open multi-agent systems. The main idea in a multi-agent system is that an intelligent global behavior can be reached from the individual behavior of the agents. In this context, it is difficulty to guarantee that the agents are correctly cooperating to reach the organization objectives in which they are inserted. The model considered in this work expands the contract concepts in components to open multi-agent system. Contracts can be understood as a negotiation form between components, which entails obligations and benefits for both parties. However, when the subject is multi-agent systems, there are a few available literatures. This is explained because contracts for components, guided on object paradigm, are hard to be translated to the characteristics of the agents. Components have methods and well defined interfaces, while agents hide their internal structures and perhaps they present complex behaviors. A framework was developed based on the conceptual model we are proposing. The result demonstrates the viability of applying contracts for components to the open multi-agents environments. The main goal is to manage and to inquire the cooperation between agents, considering the agents roles in the organization and respecting the individual agent characteristics.