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feat: Add CORS configuration for browser-based MCP clients (#1059)
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Co-authored-by: Marcelo Trylesinski <marcelotryle@gmail.com>
Co-authored-by: Felix Weinberger <fweinberger@anthropic.com>
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Jerome 2025-08-21 14:34:45 +01:00 • committed by GitHub
commit 09e3a05e13
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10
examples/servers/simple-streamablehttp-stateless/mcp_simple_streamablehttp_stateless/server.py
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@ -9,6 +9,7 @@ import mcp.types as types
from mcp.server.lowlevel import Server
from mcp.server.streamable_http_manager import StreamableHTTPSessionManager
from starlette.applications import Starlette
from starlette.middleware.cors import CORSMiddleware
from starlette.routing import Mount
from starlette.types import Receive, Scope, Send
@ -123,6 +124,15 @@ def main(
lifespan=lifespan,
)
# Wrap ASGI application with CORS middleware to expose Mcp-Session-Id header
# for browser-based clients (ensures 500 errors get proper CORS headers)
starlette_app = CORSMiddleware(
starlette_app,
allow_origins=["*"], # Allow all origins - adjust as needed for production
allow_methods=["GET", "POST", "DELETE"], # MCP streamable HTTP methods
expose_headers=["Mcp-Session-Id"],
)
import uvicorn
uvicorn.run(starlette_app, host="127.0.0.1", port=port)

10
examples/servers/simple-streamablehttp/mcp_simple_streamablehttp/server.py
View file

@ -10,6 +10,7 @@ from mcp.server.lowlevel import Server
from mcp.server.streamable_http_manager import StreamableHTTPSessionManager
from pydantic import AnyUrl
from starlette.applications import Starlette
from starlette.middleware.cors import CORSMiddleware
from starlette.routing import Mount
from starlette.types import Receive, Scope, Send
@ -148,6 +149,15 @@ def main(
lifespan=lifespan,
)
# Wrap ASGI application with CORS middleware to expose Mcp-Session-Id header
# for browser-based clients (ensures 500 errors get proper CORS headers)
starlette_app = CORSMiddleware(
starlette_app,
allow_origins=["*"], # Allow all origins - adjust as needed for production
allow_methods=["GET", "POST", "DELETE"], # MCP streamable HTTP methods
expose_headers=["Mcp-Session-Id"],
)
import uvicorn
uvicorn.run(starlette_app, host="127.0.0.1", port=port)