MCP Python SDK

import anyio import pytest from mcp.server.lowlevel import NotificationOptions, Server from mcp.server.models import InitializationOptions from mcp.types import ( LATEST_PROTOCOL_VERSION, ClientCapabilities, Implementation, InitializeRequestParams, JSONRPCMessage, JSONRPCNotification, JSONRPCRequest, NotificationParams, ) @pytest.mark.anyio async def test_request_id_match() -> None: """Test that the server preserves request IDs in responses.""" server = Server("test") custom_request_id = "test-123" # Create memory streams for communication client_writer, client_reader = anyio.create_memory_object_stream(1) server_writer, server_reader = anyio.create_memory_object_stream(1) # Server task to process the request async def run_server(): async with client_reader, server_writer: await server.run( client_reader, server_writer, InitializationOptions( server_name="test", server_version="1.0.0", capabilities=server.get_capabilities( notification_options=NotificationOptions(), experimental_capabilities={}, ), ), raise_exceptions=True, ) # Start server task async with ( anyio.create_task_group() as tg, client_writer, client_reader, server_writer, server_reader, ): tg.start_soon(run_server) # Send initialize request init_req = JSONRPCRequest( id="init-1", method="initialize", params=InitializeRequestParams( protocolVersion=LATEST_PROTOCOL_VERSION, capabilities=ClientCapabilities(), clientInfo=Implementation(name="test-client", version="1.0.0"), ).model_dump(by_alias=True, exclude_none=True), jsonrpc="2.0", ) await client_writer.send(JSONRPCMessage(root=init_req)) await server_reader.receive() # Get init response but don't need to check it # Send initialized notification initialized_notification = JSONRPCNotification( method="notifications/initialized", params=NotificationParams().model_dump(by_alias=True, exclude_none=True), jsonrpc="2.0", ) await client_writer.send(JSONRPCMessage(root=initialized_notification)) # Send ping request with custom ID ping_request = JSONRPCRequest( id=custom_request_id, method="ping", params={}, jsonrpc="2.0" ) await client_writer.send(JSONRPCMessage(root=ping_request)) # Read response response = await server_reader.receive() # Verify response ID matches request ID assert ( response.root.id == custom_request_id ), "Response ID should match request ID" # Cancel server task tg.cancel_scope.cancel()