Address kludex review comments - use __exit__ format for exception data

Changed exception data format to match Python's __exit__ format:
- exception_type: The exception class name
- exception_value: The exception message/value
- exception_traceback: The traceback (set to None for now)

Updated tests to verify the new data format.

Author: felixweinberger

src/mcp/server/lowlevel/server.py

@@ -615,10 +615,9 @@ async def _handle_message(
                     await session.send_log_message(
                         level="error",
                         data={
-                            "message": str(message),
-                            "type": type(message).__name__,
-                            "module": type(message).__module__,
-                            "args": getattr(message, "args", None),
+                            "exception_type": type(message).__name__,
+                            "exception_value": str(message),
+                            "exception_traceback": None,
                         },
                         logger="mcp.server.exception_handler",
                     )

tests/server/test_lowlevel_exception_handling.py

@@ -49,8 +49,9 @@ async def test_exception_handling_with_raise_exceptions_false(exception_class, m
     call_args = session.send_log_message.call_args
 
     assert call_args.kwargs["level"] == "error"
-    assert call_args.kwargs["data"]["message"] == str(test_exception)
-    assert call_args.kwargs["data"]["type"] == exception_class.__name__
+    assert call_args.kwargs["data"]["exception_type"] == exception_class.__name__
+    assert call_args.kwargs["data"]["exception_value"] == str(test_exception)
+    assert call_args.kwargs["data"]["exception_traceback"] is None
     assert call_args.kwargs["logger"] == "mcp.server.exception_handler"