Expose auth in connections (#236)

This PR allows connecting to mcp servers that requires OAuth.
I needed this functionality to get my langgraph agent working with
cloudflare mcp servers which have auth enabled.
This was adapted from
`modelcontextprotocol/python-sdk/`[mcp_simple_auth_client](https://github.com/modelcontextprotocol/python-sdk/tree/main/examples/clients/simple-auth-client/mcp_simple_auth_client)

Sample code for how to use
```
oauth_provider = langchain_mcp_adapters.auth.create_oauth_provider("https://mcpserver.with.oauth.org")
client = MultiServerMCPClient(
    connections={
        "server_with_auth": {
            "transport": "sse",
            "url": "https://mcpserver.with.oauth.org/sse",
            "auth": oauth_provider, #server with auth
        },
    }
)

# Get list of tools from "server_with_auth" server
async with client.session("server_with_auth") as server_with_auth_session:
    tools = await langchain_mcp_adapters.tools.load_mcp_tools(server_with_auth_session)

    print(f"\n Found {len(tools)} tools:")
    for tool in tools:
        print(f"- {tool.name}: {tool.description or 'No description'}")
```

---------

Co-authored-by: Meena Chockalingam <[email protected]>
Co-authored-by: Eugene Yurtsev <[email protected]>

Author: 3 people

langchain_mcp_adapters/sessions.py

@@ -1,14 +1,17 @@
+from __future__ import annotations
+
 import os
 from contextlib import asynccontextmanager
 from datetime import timedelta
 from pathlib import Path
-from typing import Any, AsyncIterator, Literal, Protocol, TypedDict
+from typing import Any, AsyncIterator, Literal, Protocol
 
 import httpx
 from mcp import ClientSession, StdioServerParameters
 from mcp.client.sse import sse_client
 from mcp.client.stdio import stdio_client
 from mcp.client.streamable_http import streamablehttp_client
+from typing_extensions import NotRequired, TypedDict
 
 EncodingErrorHandler = Literal["strict", "ignore", "replace"]
 
@@ -82,6 +85,9 @@ class SSEConnection(TypedDict):
     httpx_client_factory: McpHttpClientFactory | None
     """Custom factory for httpx.AsyncClient (optional)."""
 
+    auth: NotRequired[httpx.Auth]
+    """Optional authentication for the HTTP client."""
+
 
 class StreamableHttpConnection(TypedDict):
     transport: Literal["streamable_http"]
@@ -108,6 +114,9 @@ class StreamableHttpConnection(TypedDict):
     httpx_client_factory: McpHttpClientFactory | None
     """Custom factory for httpx.AsyncClient (optional)."""
 
+    auth: NotRequired[httpx.Auth]
+    """Optional authentication for the HTTP client."""
+
 
 class WebsocketConnection(TypedDict):
     transport: Literal["websocket"]
@@ -175,6 +184,7 @@ async def _create_sse_session(
     sse_read_timeout: float = DEFAULT_SSE_READ_TIMEOUT,
     session_kwargs: dict[str, Any] | None = None,
     httpx_client_factory: McpHttpClientFactory | None = None,
+    auth: httpx.Auth | None = None,
 ) -> AsyncIterator[ClientSession]:
     """Create a new session to an MCP server using SSE.
 
@@ -185,13 +195,17 @@ async def _create_sse_session(
         sse_read_timeout: SSE read timeout
         session_kwargs: Additional keyword arguments to pass to the ClientSession
         httpx_client_factory: Custom factory for httpx.AsyncClient (optional)
+        auth: httpx.Auth | None = None
     """
     # Create and store the connection
     kwargs = {}
     if httpx_client_factory is not None:
         kwargs["httpx_client_factory"] = httpx_client_factory
 
-    async with sse_client(url, headers, timeout, sse_read_timeout, **kwargs) as (read, write):
+    async with sse_client(url, headers, timeout, sse_read_timeout, auth=auth, **kwargs) as (
+        read,
+        write,
+    ):
         async with ClientSession(read, write, **(session_kwargs or {})) as session:
             yield session
 
@@ -206,6 +220,7 @@ async def _create_streamable_http_session(
     terminate_on_close: bool = True,
     session_kwargs: dict[str, Any] | None = None,
     httpx_client_factory: McpHttpClientFactory | None = None,
+    auth: httpx.Auth | None = None,
 ) -> AsyncIterator[ClientSession]:
     """Create a new session to an MCP server using Streamable HTTP.
 
@@ -217,14 +232,15 @@ async def _create_streamable_http_session(
         terminate_on_close: Whether to terminate the session on close
         session_kwargs: Additional keyword arguments to pass to the ClientSession
         httpx_client_factory: Custom factory for httpx.AsyncClient (optional)
+        auth: httpx.Auth | None = None
     """
     # Create and store the connection
     kwargs = {}
     if httpx_client_factory is not None:
         kwargs["httpx_client_factory"] = httpx_client_factory
 
     async with streamablehttp_client(
-        url, headers, timeout, sse_read_timeout, terminate_on_close, **kwargs
+        url, headers, timeout, sse_read_timeout, terminate_on_close, auth=auth, **kwargs
     ) as (read, write, _):
         async with ClientSession(read, write, **(session_kwargs or {})) as session:
             yield session
@@ -295,6 +311,7 @@ async def create_session(
             sse_read_timeout=connection.get("sse_read_timeout", DEFAULT_SSE_READ_TIMEOUT),
             session_kwargs=connection.get("session_kwargs"),
             httpx_client_factory=connection.get("httpx_client_factory"),
+            auth=connection.get("auth"),
         ) as session:
             yield session
     elif transport == "streamable_http":
@@ -309,6 +326,7 @@ async def create_session(
             ),
             session_kwargs=connection.get("session_kwargs"),
             httpx_client_factory=connection.get("httpx_client_factory"),
+            auth=connection.get("auth"),
         ) as session:
             yield session
     elif transport == "stdio":

pyproject.toml

@@ -16,6 +16,7 @@ requires-python = ">=3.10"
 dependencies = [
     "langchain-core>=0.3.36,<0.4",
     "mcp>=1.9.2",
+    "typing-extensions>=4.14.0",
 ]
 
 [dependency-groups]