YouTip

# LangChain Messages API * * * ## All Message Types | Type | role | type | Key Attributes | Description | | --- | --- | --- | --- | --- | | HumanMessage | user | human | content | User message | | AIMessage | assistant | ai | content, tool_calls, usage_metadata | AI response | | AIMessageChunk | assistant | ai | content (incremental) | Streaming token chunks | | SystemMessage | system | system | content | System instruction | | ToolMessage | tool | tool | content, tool_call_id, name | Tool execution result | | RemoveMessage | - | remove | id | Delete specified message | * * * ## ContentBlock Types (Multimodal Content) | Type | Description | Use Case | | --- | --- | --- | | PlainTextContentBlock | Plain text | Regular text | | ImageContentBlock | Image (base64 or URL) | Image input for multimodal models | | AudioContentBlock | Audio | Voice input | | VideoContentBlock | Video | Video input | | FileContentBlock | File | Document input | | ToolCall | Tool call request | Model requests to call a tool | | ServerToolCall | Server-side tool call | Server-side tool invocation |