API reference

LangChain API reference

framework for context-aware reasoning applications, pre-built agents, and LLM orchestration

Topics covered

Name	What it does
`AgentExecutor`	Class
`BaseChatModel`	Class
`AIMessage`	Class
`HumanMessage`	Class
`SystemMessage`	Class
`ToolMessage`	Class
`BaseTool`	Class
`StructuredTool`	Class
`HumanInTheLoopMiddleware`	Class
`ModelCallLimitMiddleware`	Class
`ToolCallLimitMiddleware`	Class
`ClearToolUsesEdit`	Class
`MCPAdapter`	Class
`MCPElicitationRequest`	Class
`MCPElicitationInterrupt`	Class
`MCPElicitationAccept`	Class
`MCPToolArtifact`	Class
`ChatPromptTemplate`	Class
`PromptTemplate`	Class
`RunnableSequence`	Class
`RunnableParallel`	Class
`RunnableLambda`	Class
`RunnablePassthrough`	Class
`Document`	Class
`RecursiveCharacterTextSplitter`	Class
`StrOutputParser`	Class
`JsonOutputParser`	Class
`PydanticOutputParser`	Class
`AgentMiddleware`	Class
`ModelRequest`	Class
`SummarizationMiddleware`	Class
`PIIMiddleware`	Class
`ModelFallbackMiddleware`	Class
`ModelRetryMiddleware`	Class
`ToolRetryMiddleware`	Class
`TodoListMiddleware`	Class
`LLMToolSelectorMiddleware`	Class
`ContextEditingMiddleware`	Class
`ShellToolMiddleware`	Class
`ToolStrategy`	Class
`ProviderStrategy`	Class
`InMemoryRateLimiter`	Class
`ToolRuntime`	Class

Name	What it does
`AgentState`	Type Alias
`RunnableConfig`	Type Alias

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