LangChain Messages

Represents a chunk of an AI message, which can be concatenated with

Base class for all types of messages in a conversation. It includes

Represents a chunk of a message, which can be concatenated with other

Interface for interacting with a document.

A tool that can be created dynamically from a function, name, and

A tool that can be created dynamically from a function, name, and description.

Represents a human message in a conversation.

Represents a chunk of a human message, which can be concatenated with

In-memory implementation of the BaseStore using a dictionary. Used for

Base class for Tools that accept input of any shape defined by a Zod schema.

Represents a system message in a conversation.

Represents a chunk of a system message, which can be concatenated with

Base class for Tools that accept input as a string.

Represents a tool message in a conversation.

Represents a chunk of a tool message, which can be concatenated

LangChain Messages

Represents a chunk of an AI message, which can be concatenated with

Base class for all types of messages in a conversation. It includes

Represents a chunk of a message, which can be concatenated with other

Strategy for clearing tool outputs when token limits are exceeded.

Interface for interacting with a document.

A tool that can be created dynamically from a function, name, and

A tool that can be created dynamically from a function, name, and description.

Fake chat model for testing tool calling functionality

Represents a human message in a conversation.

Represents a chunk of a human message, which can be concatenated with

In-memory implementation of the BaseStore using a dictionary. Used for

Error thrown when a middleware fails.

Raised when model returns multiple structured output tool calls when only one is expected.

Error thrown when PII is detected and strategy is 'block'

Raised when structured output tool call arguments fail to parse according to the schema.

Base class for Tools that accept input of any shape defined by a Zod schema.

Represents a system message in a conversation.

Represents a chunk of a system message, which can be concatenated with

Base class for Tools that accept input as a string.

Exception raised when tool call limits are exceeded.

Raised when a tool call is throwing an error.

Represents a tool message in a conversation.

Represents a chunk of a tool message, which can be concatenated

Information for tracking structured output tool metadata.

Class that provides a layer of abstraction over the base storage,

File system implementation of the BaseStore using a dictionary. Used for

In-memory implementation of the BaseStore using a dictionary. Used for

LangChain utilities

LangChain Testing Utilities

LangChain Messages

Initialize a ChatModel from the model name and provider.

LangChain Tools

LangChain Messages

Attempts to infer the model provider based on the given model name.

Helper function to get a chat model class by its class name or model provider.

Initialize a ChatModel from the model name and provider.

Pull a prompt from the hub.

Push a prompt to the hub.

Infer modelProvider from the id namespace to avoid className collisions.

Pull a prompt from the hub.

Push a prompt to the hub.

Creates a prompt caching middleware for Anthropic models to optimize API usage.

Apply strategy to content based on matches

LangChain utilities

Middleware that automatically prunes tool results to manage context size.

Default token counter that approximates based on character count.

Creates a production-ready ReAct (Reasoning + Acting) agent that combines language models with tools

Creates a middleware instance with automatic schema inference.

Detect credit card numbers in content (validated with Luhn algorithm)

Detect email addresses in content

Detect IP addresses in content (validated)

Detect MAC addresses in content

Detect URLs in content

Dynamic System Prompt Middleware

LangChain Testing Utilities

LangChain Messages

Creates a Human-in-the-Loop (HITL) middleware for tool approval and oversight.

Middleware for selecting tools using an LLM-based strategy.

Creates a middleware to limit the number of model calls at both thread and run levels.

Middleware that provides automatic model fallback on errors.

Middleware that automatically retries failed model calls with configurable backoff.

Provider specific middleware

Creates a middleware that detects and handles personally identifiable information (PII)

Creates a provider strategy for structured output using native JSON schema support.

Resolve a redaction rule to a concrete detector function

Summarization middleware that automatically summarizes conversation history when token limits are approached.

Creates a middleware that provides todo list management capabilities to agents.

LangChain Tools

Middleware that tracks tool call counts and enforces limits.

Middleware that emulates specified tools using an LLM instead of executing them.

Middleware that automatically retries failed tool calls with configurable backoff.

Creates a tool strategy for structured output using function calling.

LangChain Messages

Initialize a ChatModel from the model name and provider.

Load a LangChain module from a serialized text representation.

Get a unique name for the module, rather than parent class implementations.

LangChain Messages

LangChain Documents

LangChain Testing Utilities

Content block to represent an invalid tool call

Represents a request to call a tool.

Content block to represent partial data of a tool call

Annotation for citing data from a document.

Provider-specific content block.

Reasoning output from a LLM.

Text output from a LLM.

Represents an action with a name and arguments.

Represents an action request with a name, arguments, and description.

Base middleware interface.

Type bag that encapsulates all agent type parameters.

Response when a human approves the action.

Configuration for clearing tool outputs when token limits are exceeded.

LangChain Messages

Protocol describing a context editing strategy.

Configuration for the Context Editing Middleware.

Default type configuration for agents.

LangChain Documents

Response when a human edits the action.

Information about a tool call that has been executed.

Request for human feedback on a sequence of actions requested by a model.

Response payload for a HITLRequest.

Represents information about an interrupt.

LangChain Testing Utilities

Type bag that encapsulates all middleware type parameters.

Configuration for modifying a model call at runtime.

Options for configuring the OpenAI Moderation middleware.

Represents a detected PII match in content

ReactAgent is a production-ready ReAct (Reasoning + Acting) agent that combines

Configuration for a redaction rule

Response when a human rejects the action.

Resolved redaction rule with a concrete detector function

Policy for reviewing a HITL request.

Information about a tool call that has been executed.

Represents a tool call request for the wrapToolCall hook.

Options for configuring the Tool Emulator middleware.

Information about a tool result from a tool execution.

Branded type for ToolStrategy arrays that preserves type information

Interface for objects that can be serialized.

Runtime context automatically injected into tools.

Content block for audio data

Content block for multimodal data

Content block for file data

Content block for image data

Content block for plain text data

Content block for video data

Hook type for the afterAgent lifecycle event.

Hook type for the afterModel lifecycle event.

Hook type for the beforeAgent lifecycle event.

Hook type for the beforeModel lifecycle event.

Built-in PII types

Helper type to combine agent tools with middleware tools into a single readonly array.

Union of all possible decision types.

Default type configuration for middleware.

Function type that dynamically generates a description for a tool call approval request.

Type helper to extract union type from an array of Zod schemas

Helper type to infer the full merged context from an agent, including:

Shorthand helper to extract the raw Context schema type from an AgentTypeConfig or ReactAgent.

Shorthand helper to extract the Middleware type from an AgentTypeConfig or ReactAgent.

Shorthand helper to extract the Response type from an AgentTypeConfig or ReactAgent.

Helper type to infer the full merged state from an agent, including:

Shorthand helper to extract the raw State schema type from an AgentTypeConfig or ReactAgent.

Shorthand helper to extract the Tools type from an AgentTypeConfig or ReactAgent.

Helper type to extract any property from an AgentTypeConfig or ReactAgent.

Helper type to extract input type from context schema (with optional defaults)

Helper type to infer merged input state from an array of middleware (includes built-in state)

Helper type to infer merged state from an array of middleware (includes built-in state)

Helper type to infer the context schema type from a middleware

Helper type to infer the input context schema type from a middleware (with optional defaults)

Helper type to infer merged input context from an array of middleware (with optional defaults)

Helper type to infer merged context from an array of middleware

Shorthand helper to extract the ContextSchema type from a MiddlewareTypeConfig or AgentMiddleware.

Shorthand helper to extract the FullContext type from a MiddlewareTypeConfig or AgentMiddleware.

Helper type to infer the input state schema type from a middleware (all properties optional)

Helper type to infer merged input state from an array of middleware (with optional defaults)

Shorthand helper to extract the Schema type from a MiddlewareTypeConfig or AgentMiddleware.

Helper type to infer the state schema type from a middleware

Helper type to infer merged state from an array of middleware (just the middleware states)

Helper type to infer tools from a single middleware instance.

Helper type to infer and merge tools from an array of middleware.

Shorthand helper to extract the Tools type from a MiddlewareTypeConfig or AgentMiddleware.

Helper type to extract any property from a MiddlewareTypeConfig or AgentMiddleware.

jump targets (internal)

Result type for middleware functions.

Custom detector function that takes content and returns matches

Strategy for handling detected PII

Helper type to resolve an AgentTypeConfig from either:

Helper type to resolve a MiddlewareTypeConfig from either:

Special type to indicate that no response format is provided.

Runtime information available to middleware (readonly).

Handler function type for wrapping tool calls.

Runtime context automatically injected into tools.

Helper type to convert an array of tools (ClientTool | ServerTool)[] to a MessageToolSet.

Base input type for .invoke and .stream methods.

Handler function type for wrapping model calls.

Wrapper function type for the wrapModelCall hook.

Wrapper function type for the wrapToolCall hook.