Agora is a simple cross-platform protocol that allows heterogeneous large language models (LLMs) to communicate effectively with each other through negotiation. The protocol facilitates rare communication in natural language while negotiating a structured data communication protocol (e.g., JSON) for frequent interactions. Once the protocol is established, LLMs will utilize routines—simple scripts (e.g., Python)—for sending or receiving data. Future communications will leverage these routines, reducing dependency on LLMs and enhancing efficiency, versatility, and portability.