fix: exit stdio server cleanly on interrupt

Author: he-yufeng

src/mcp/server/mcpserver/server.py

@@ -291,13 +291,16 @@ def run(
         if transport not in TRANSPORTS.__args__:  # type: ignore  # pragma: no cover
             raise ValueError(f"Unknown transport: {transport}")
 
-        match transport:
-            case "stdio":
-                anyio.run(self.run_stdio_async)
-            case "sse":  # pragma: no cover
-                anyio.run(lambda: self.run_sse_async(**kwargs))
-            case "streamable-http":  # pragma: no cover
-                anyio.run(lambda: self.run_streamable_http_async(**kwargs))
+        try:
+            match transport:
+                case "stdio":
+                    anyio.run(self.run_stdio_async)
+                case "sse":  # pragma: no cover
+                    anyio.run(lambda: self.run_sse_async(**kwargs))
+                case "streamable-http":  # pragma: no cover
+                    anyio.run(lambda: self.run_streamable_http_async(**kwargs))
+        except KeyboardInterrupt:
+            return
 
     async def _handle_list_tools(
         self, ctx: ServerRequestContext[LifespanResultT], params: PaginatedRequestParams | None

tests/server/mcpserver/test_server.py

@@ -74,6 +74,14 @@ def test_dependencies(self):
         mcp_no_deps = MCPServer("test")
         assert mcp_no_deps.dependencies == []
 
+    def test_stdio_keyboard_interrupt_exits_cleanly(self):
+        mcp = MCPServer("test")
+
+        with patch("mcp.server.mcpserver.server.anyio.run", side_effect=KeyboardInterrupt) as run:
+            mcp.run("stdio")
+
+        run.assert_called_once_with(mcp.run_stdio_async)
+
     async def test_sse_app_returns_starlette_app(self):
         """Test that sse_app returns a Starlette application with correct routes."""
         mcp = MCPServer("test")