[#toolmessage](https://js.langchain.com/docs/concepts/messages/#toolmessage): LLM should read this page when needing to understand how messages work in chat models, when needing to work with messages in a unified format across different chat model providers, and when needing to understand the structure and content of conversations with chat models. Messages are the unit of communication in chat models, representing input/output and metadata; LangChain provides a unified message format and classes like HumanMessage, AIMessage, and ToolMessage to work with messages in a standardized way across different chat model providers.

