diff --git a/polymind/core/tool.py b/polymind/core/tool.py
index 9047b47..a27ad68 100644
--- a/polymind/core/tool.py
+++ b/polymind/core/tool.py
@@ -278,7 +278,7 @@ async def _execute(self, input: Message) -> Message:
         pass
 
 
-class OptimizableBaseTool(AbstractTool, dspy.Predict):
+class OptimizableBaseTool(AbstractTool, dspy.Predict, metaclass=type(BaseModel)):
     def __call__(self, input: Message) -> Message:
         self._validate_input_message(input)
         output_message = self.forward(**input.content)
diff --git a/pyproject.toml b/pyproject.toml
index ff05033..cdc91a4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "polymind"
-version = "0.0.55"  # Update this version before publishing to PyPI
+version = "0.0.56"  # Update this version before publishing to PyPI
 description = "PolyMind is a customizable collaborative multi-agent framework for collective intelligence and distributed problem solving."
 authors = ["TechTao"]
 license = "MIT License"
@@ -49,7 +49,7 @@ skip = ["__init__.py"]
 [tool.flake8]
 max-line-length = 120
 exclude = ["__init__.py"]
-ignore = ["Q000"]
+ignore = ["Q000", "E203"]
 
 [build-system]
 requires = ["poetry-core"]