Langchain Adapter

This module implements the LangChain adapter.

LangChain tools support both sync and async functions for their tools so we can leverage both in our implementation.

Example Usage:

with MCPAdapt(StdioServerParameters(command="uv", args=["run", "src/echo.py"]), LangChainAdapter()) as tools: print(tools)

LangChainAdapter

Bases: ToolAdapter

Adapter for langchain.

Note that langchain support both sync and async tools so we write adapt for both methods.

Warning: if the mcp tool name is a python keyword, starts with digits or contains dashes, the tool name will be sanitized to become a valid python function name.

Source code in src/mcpadapt/langchain_adapter.py

class LangChainAdapter(ToolAdapter):
    """Adapter for `langchain`.

    Note that `langchain` support both sync and async tools so we
    write adapt for both methods.

    Warning: if the mcp tool name is a python keyword, starts with digits or contains
    dashes, the tool name will be sanitized to become a valid python function name.

    """

    def adapt(
        self,
        func: Callable[[dict | None], mcp.types.CallToolResult],
        mcp_tool: mcp.types.Tool,
    ) -> BaseTool:
        """Adapt a MCP tool to a LangChain tool.

        Args:
            func: The function to adapt.
            mcp_tool: The MCP tool to adapt.

        Returns:
            A LangChain tool.
        """
        mcp_tool_name = _sanitize_function_name(mcp_tool.name)

        generate_class_template = partial(
            _generate_tool_class,
            mcp_tool_name,
            mcp_tool.description,
            mcp_tool.inputSchema,
            False,
        )
        return _instanciate_tool(mcp_tool_name, generate_class_template, func)

    def async_adapt(
        self,
        afunc: Callable[[dict | None], Coroutine[Any, Any, mcp.types.CallToolResult]],
        mcp_tool: mcp.types.Tool,
    ) -> BaseTool:
        """Adapt a MCP tool to a LangChain tool.

        Args:
            afunc: The function to adapt.
            mcp_tool: The MCP tool to adapt.

        Returns:
            A LangChain tool.
        """
        mcp_tool_name = _sanitize_function_name(mcp_tool.name)
        if mcp_tool_name != mcp_tool.name:
            log.warning(f"MCP tool name {mcp_tool.name} sanitized to {mcp_tool_name}")

        generate_class_template = partial(
            _generate_tool_class,
            mcp_tool_name,
            mcp_tool.description,
            mcp_tool.inputSchema,
            True,
        )
        return _instanciate_tool(mcp_tool_name, generate_class_template, afunc)

adapt

adapt(
    func: Callable[[dict | None], CallToolResult],
    mcp_tool: Tool,
) -> BaseTool

Adapt a MCP tool to a LangChain tool.

Parameters:

Name	Type	Description	Default
func	Callable[[dict | None], CallToolResult]	The function to adapt.	required
mcp_tool	Tool	The MCP tool to adapt.	required

Returns:

Type	Description
BaseTool	A LangChain tool.

Source code in src/mcpadapt/langchain_adapter.py

def adapt(
    self,
    func: Callable[[dict | None], mcp.types.CallToolResult],
    mcp_tool: mcp.types.Tool,
) -> BaseTool:
    """Adapt a MCP tool to a LangChain tool.

    Args:
        func: The function to adapt.
        mcp_tool: The MCP tool to adapt.

    Returns:
        A LangChain tool.
    """
    mcp_tool_name = _sanitize_function_name(mcp_tool.name)

    generate_class_template = partial(
        _generate_tool_class,
        mcp_tool_name,
        mcp_tool.description,
        mcp_tool.inputSchema,
        False,
    )
    return _instanciate_tool(mcp_tool_name, generate_class_template, func)

async_adapt

async_adapt(
    afunc: Callable[
        [dict | None], Coroutine[Any, Any, CallToolResult]
    ],
    mcp_tool: Tool,
) -> BaseTool

Adapt a MCP tool to a LangChain tool.

Parameters:

Name	Type	Description	Default
afunc	Callable[[dict | None], Coroutine[Any, Any, CallToolResult]]	The function to adapt.	required
mcp_tool	Tool	The MCP tool to adapt.	required

Returns:

Type	Description
BaseTool	A LangChain tool.

Source code in src/mcpadapt/langchain_adapter.py

def async_adapt(
    self,
    afunc: Callable[[dict | None], Coroutine[Any, Any, mcp.types.CallToolResult]],
    mcp_tool: mcp.types.Tool,
) -> BaseTool:
    """Adapt a MCP tool to a LangChain tool.

    Args:
        afunc: The function to adapt.
        mcp_tool: The MCP tool to adapt.

    Returns:
        A LangChain tool.
    """
    mcp_tool_name = _sanitize_function_name(mcp_tool.name)
    if mcp_tool_name != mcp_tool.name:
        log.warning(f"MCP tool name {mcp_tool.name} sanitized to {mcp_tool_name}")

    generate_class_template = partial(
        _generate_tool_class,
        mcp_tool_name,
        mcp_tool.description,
        mcp_tool.inputSchema,
        True,
    )
    return _instanciate_tool(mcp_tool_name, generate_class_template, afunc)