Introduce a function to create a standard AsyncClient with options (#655)

examples/servers/simple-auth/mcp_simple_auth/server.py

@@ -6,7 +6,6 @@ import time
 from typing import Any
 
 import click
-import httpx
 from pydantic import AnyHttpUrl
 from pydantic_settings import BaseSettings, SettingsConfigDict
 from starlette.exceptions import HTTPException
@@ -24,6 +23,7 @@ from mcp.server.auth.provider import (
 )
 from mcp.server.auth.settings import AuthSettings, ClientRegistrationOptions
 from mcp.server.fastmcp.server import FastMCP
+from mcp.shared._httpx_utils import create_mcp_http_client
 from mcp.shared.auth import OAuthClientInformationFull, OAuthToken
 
 logger = logging.getLogger(__name__)
@@ -123,7 +123,7 @@ class SimpleGitHubOAuthProvider(OAuthAuthorizationServerProvider):
         client_id = state_data["client_id"]
 
         # Exchange code for token with GitHub
-        async with httpx.AsyncClient() as client:
+        async with create_mcp_http_client() as client:
             response = await client.post(
                 self.settings.github_token_url,
                 data={
@@ -325,7 +325,7 @@ def create_simple_mcp_server(settings: ServerSettings) -> FastMCP:
         """
         github_token = get_github_token()
 
-        async with httpx.AsyncClient() as client:
+        async with create_mcp_http_client() as client:
             response = await client.get(
                 "https://api.github.com/user",
                 headers={

examples/servers/simple-tool/mcp_simple_tool/server.py

@@ -1,8 +1,8 @@
 import anyio
 import click
-import httpx
 import mcp.types as types
 from mcp.server.lowlevel import Server
+from mcp.shared._httpx_utils import create_mcp_http_client
 
 
 async def fetch_website(
@@ -11,7 +11,7 @@ async def fetch_website(
     headers = {
         "User-Agent": "MCP Test Server (github.com/modelcontextprotocol/python-sdk)"
     }
-    async with httpx.AsyncClient(follow_redirects=True, headers=headers) as client:
+    async with create_mcp_http_client(headers=headers) as client:
         response = await client.get(url)
         response.raise_for_status()
         return [types.TextContent(type="text", text=response.text)]

src/mcp/client/sse.py

@@ -10,6 +10,7 @@ from anyio.streams.memory import MemoryObjectReceiveStream, MemoryObjectSendStre
 from httpx_sse import aconnect_sse
 
 import mcp.types as types
+from mcp.shared._httpx_utils import create_mcp_http_client
 from mcp.shared.message import SessionMessage
 
 logger = logging.getLogger(__name__)
@@ -44,7 +45,7 @@ async def sse_client(
     async with anyio.create_task_group() as tg:
         try:
             logger.info(f"Connecting to SSE endpoint: {remove_request_params(url)}")
-            async with httpx.AsyncClient(headers=headers) as client:
+            async with create_mcp_http_client(headers=headers) as client:
                 async with aconnect_sse(
                     client,
                     "GET",

src/mcp/client/streamable_http.py

@@ -18,6 +18,7 @@ import httpx
 from anyio.streams.memory import MemoryObjectReceiveStream, MemoryObjectSendStream
 from httpx_sse import EventSource, ServerSentEvent, aconnect_sse
 
+from mcp.shared._httpx_utils import create_mcp_http_client
 from mcp.shared.message import ClientMessageMetadata, SessionMessage
 from mcp.types import (
     ErrorData,
@@ -446,12 +447,11 @@ async def streamablehttp_client(
         try:
             logger.info(f"Connecting to StreamableHTTP endpoint: {url}")
 
-            async with httpx.AsyncClient(
+            async with create_mcp_http_client(
                 headers=transport.request_headers,
                 timeout=httpx.Timeout(
                     transport.timeout.seconds, read=transport.sse_read_timeout.seconds
                 ),
-                follow_redirects=True,
             ) as client:
                 # Define callbacks that need access to tg
                 def start_get_stream() -> None:

src/mcp/shared/_httpx_utils.py

@@ -0,0 +1,62 @@
+"""Utilities for creating standardized httpx AsyncClient instances."""
+
+from typing import Any
+
+import httpx
+
+__all__ = ["create_mcp_http_client"]
+
+
+def create_mcp_http_client(
+    headers: dict[str, str] | None = None,
+    timeout: httpx.Timeout | None = None,
+) -> httpx.AsyncClient:
+    """Create a standardized httpx AsyncClient with MCP defaults.
+
+    This function provides common defaults used throughout the MCP codebase:
+    - follow_redirects=True (always enabled)
+    - Default timeout of 30 seconds if not specified
+
+    Args:
+        headers: Optional headers to include with all requests.
+        timeout: Request timeout as httpx.Timeout object.
+            Defaults to 30 seconds if not specified.
+
+    Returns:
+        Configured httpx.AsyncClient instance with MCP defaults.
+
+    Note:
+        The returned AsyncClient must be used as a context manager to ensure
+        proper cleanup of connections.
+
+    Examples:
+        # Basic usage with MCP defaults
+        async with create_mcp_http_client() as client:
+            response = await client.get("https://api.example.com")
+
+        # With custom headers
+        headers = {"Authorization": "Bearer token"}
+        async with create_mcp_http_client(headers) as client:
+            response = await client.get("/endpoint")
+
+        # With both custom headers and timeout
+        timeout = httpx.Timeout(60.0, read=300.0)
+        async with create_mcp_http_client(headers, timeout) as client:
+            response = await client.get("/long-request")
+    """
+    # Set MCP defaults
+    kwargs: dict[str, Any] = {
+        "follow_redirects": True,
+    }
+
+    # Handle timeout
+    if timeout is None:
+        kwargs["timeout"] = httpx.Timeout(30.0)
+    else:
+        kwargs["timeout"] = timeout
+
+    # Handle headers
+    if headers is not None:
+        kwargs["headers"] = headers
+
+    return httpx.AsyncClient(**kwargs)

tests/shared/test_httpx_utils.py

@@ -0,0 +1,24 @@
+"""Tests for httpx utility functions."""
+
+import httpx
+
+from mcp.shared._httpx_utils import create_mcp_http_client
+
+
+def test_default_settings():
+    """Test that default settings are applied correctly."""
+    client = create_mcp_http_client()
+
+    assert client.follow_redirects is True
+    assert client.timeout.connect == 30.0
+
+
+def test_custom_parameters():
+    """Test custom headers and timeout are set correctly."""
+    headers = {"Authorization": "Bearer token"}
+    timeout = httpx.Timeout(60.0)
+
+    client = create_mcp_http_client(headers, timeout)
+
+    assert client.headers["Authorization"] == "Bearer token"
+    assert client.timeout.connect == 60.0