add auth client sse (#760)

examples/clients/simple-auth-client/README.md

@@ -1,11 +1,11 @@
 # Simple Auth Client Example
 
-A demonstration of how to use the MCP Python SDK with OAuth authentication over streamable HTTP transport.
+A demonstration of how to use the MCP Python SDK with OAuth authentication over streamable HTTP or SSE transport.
 
 ## Features
 
 - OAuth 2.0 authentication with PKCE
-- Streamable HTTP transport  
+- Support for both StreamableHTTP and SSE transports
 - Interactive command-line interface
 
 ## Installation
@@ -31,7 +31,10 @@ uv run mcp-simple-auth --transport streamable-http --port 3001
 uv run mcp-simple-auth-client
 
 # Or with custom server URL
-MCP_SERVER_URL=http://localhost:3001 uv run mcp-simple-auth-client
+MCP_SERVER_PORT=3001 uv run mcp-simple-auth-client
+
+# Use SSE transport
+MCP_TRANSPORT_TYPE=sse uv run mcp-simple-auth-client
 ```
 
 ### 3. Complete OAuth flow
@@ -67,4 +70,5 @@ mcp> quit
 
 ## Configuration
 
-- `MCP_SERVER_URL` - Server URL (default: http://localhost:3001)
+- `MCP_SERVER_PORT` - Server URL (default: 8000)
+- `MCP_TRANSPORT_TYPE` - Transport type: `streamable_http` (default) or `sse`

examples/clients/simple-auth-client/mcp_simple_auth_client/main.py

@@ -18,6 +18,7 @@ from urllib.parse import parse_qs, urlparse
 
 from mcp.client.auth import OAuthClientProvider, TokenStorage
 from mcp.client.session import ClientSession
+from mcp.client.sse import sse_client
 from mcp.client.streamable_http import streamablehttp_client
 from mcp.shared.auth import OAuthClientInformationFull, OAuthClientMetadata, OAuthToken
 
@@ -149,8 +150,9 @@ class CallbackServer:
 class SimpleAuthClient:
     """Simple MCP client with auth support."""
 
-    def __init__(self, server_url: str):
+    def __init__(self, server_url: str, transport_type: str = "streamable_http"):
         self.server_url = server_url
+        self.transport_type = transport_type
         self.session: ClientSession | None = None
 
     async def connect(self):
@@ -195,31 +197,23 @@ class SimpleAuthClient:
                 callback_handler=callback_handler,
             )
 
-            # Create streamable HTTP transport with auth handler
-            stream_context = streamablehttp_client(
-                url=self.server_url,
-                auth=oauth_auth,
-                timeout=timedelta(seconds=60),
-            )
-
-            print(
-                "📡 Opening transport connection (HTTPX handles auth automatically)..."
-            )
-            async with stream_context as (read_stream, write_stream, get_session_id):
-                print("🤝 Initializing MCP session...")
-                async with ClientSession(read_stream, write_stream) as session:
-                    self.session = session
-                    print("⚡ Starting session initialization...")
-                    await session.initialize()
-                    print("✨ Session initialization complete!")
-
-                    print(f"\n✅ Connected to MCP server at {self.server_url}")
-                    session_id = get_session_id()
-                    if session_id:
-                        print(f"Session ID: {session_id}")
-
-                    # Run interactive loop
-                    await self.interactive_loop()
+            # Create transport with auth handler based on transport type
+            if self.transport_type == "sse":
+                print("📡 Opening SSE transport connection with auth...")
+                async with sse_client(
+                    url=self.server_url,
+                    auth=oauth_auth,
+                    timeout=60,
+                ) as (read_stream, write_stream):
+                    await self._run_session(read_stream, write_stream, None)
+            else:
+                print("📡 Opening StreamableHTTP transport connection with auth...")
+                async with streamablehttp_client(
+                    url=self.server_url,
+                    auth=oauth_auth,
+                    timeout=timedelta(seconds=60),
+                ) as (read_stream, write_stream, get_session_id):
+                    await self._run_session(read_stream, write_stream, get_session_id)
 
         except Exception as e:
             print(f"❌ Failed to connect: {e}")
@@ -227,6 +221,24 @@ class SimpleAuthClient:
 
             traceback.print_exc()
 
+    async def _run_session(self, read_stream, write_stream, get_session_id):
+        """Run the MCP session with the given streams."""
+        print("🤝 Initializing MCP session...")
+        async with ClientSession(read_stream, write_stream) as session:
+            self.session = session
+            print("⚡ Starting session initialization...")
+            await session.initialize()
+            print("✨ Session initialization complete!")
+
+            print(f"\n✅ Connected to MCP server at {self.server_url}")
+            if get_session_id:
+                session_id = get_session_id()
+                if session_id:
+                    print(f"Session ID: {session_id}")
+
+            # Run interactive loop
+            await self.interactive_loop()
+
     async def list_tools(self):
         """List available tools from the server."""
         if not self.session:
@@ -326,13 +338,20 @@ async def main():
     """Main entry point."""
     # Default server URL - can be overridden with environment variable
     # Most MCP streamable HTTP servers use /mcp as the endpoint
-    server_url = os.getenv("MCP_SERVER_URL", "http://localhost:8000/mcp")
+    server_url = os.getenv("MCP_SERVER_PORT", 8000)
+    transport_type = os.getenv("MCP_TRANSPORT_TYPE", "streamable_http")
+    server_url = (
+        f"http://localhost:{server_url}/mcp"
+        if transport_type == "streamable_http"
+        else f"http://localhost:{server_url}/sse"
+    )
 
     print("🚀 Simple MCP Auth Client")
     print(f"Connecting to: {server_url}")
+    print(f"Transport type: {transport_type}")
 
     # Start connection flow - OAuth will be handled automatically
-    client = SimpleAuthClient(server_url)
+    client = SimpleAuthClient(server_url, transport_type)
     await client.connect()
 
 

src/mcp/client/sse.py

@@ -26,12 +26,20 @@ async def sse_client(
     headers: dict[str, Any] | None = None,
     timeout: float = 5,
     sse_read_timeout: float = 60 * 5,
+    auth: httpx.Auth | None = None,
 ):
     """
     Client transport for SSE.
 
     `sse_read_timeout` determines how long (in seconds) the client will wait for a new
     event before disconnecting. All other HTTP operations are controlled by `timeout`.
+
+    Args:
+        url: The SSE endpoint URL.
+        headers: Optional headers to include in requests.
+        timeout: HTTP timeout for regular operations.
+        sse_read_timeout: Timeout for SSE read operations.
+        auth: Optional HTTPX authentication handler.
     """
     read_stream: MemoryObjectReceiveStream[SessionMessage | Exception]
     read_stream_writer: MemoryObjectSendStream[SessionMessage | Exception]
@@ -45,7 +53,7 @@ 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 create_mcp_http_client(headers=headers) as client:
+            async with create_mcp_http_client(headers=headers, auth=auth) as client:
                 async with aconnect_sse(
                     client,
                     "GET",