* Remove handling of out-of-spec 'notification/stderr' messages. It's not a thing. See https://github.com/modelcontextprotocol/servers/pull/2469

* Inspect the stderr output of STDIO servers and attempt to assign an appropriate RFC 5424 Syslog Protocol level before sending a leveled logging message to the client

server/src/index.ts

@@ -458,7 +458,7 @@ app.get(
               level,
               logger: "stdio",
               data: {
-                error: message,
+                message,
               },
             },
           });