fix(toolbox-core): honor explicit defaults and clean lint issues

Author: Deeven-Seru

packages/toolbox-core/src/toolbox_core/protocol.py

@@ -83,6 +83,11 @@ class ParameterSchema(BaseModel):
     additionalProperties: Optional[Union[bool, AdditionalPropertiesSchema]] = None
     default: Optional[Any] = None
 
+    @property
+    def has_default(self) -> bool:
+        """Returns True if `default` was explicitly provided in schema input."""
+        return "default" in self.model_fields_set
+
     def __get_type(self) -> Type:
         base_type: Type
         if self.type == "array":
@@ -105,7 +110,7 @@ def __get_type(self) -> Type:
 
     def to_param(self) -> Parameter:
         default_value = Parameter.empty
-        if self.default is not None:
+        if self.has_default:
             default_value = self.default
         elif not self.required:
             default_value = None

packages/toolbox-core/src/toolbox_core/tool.py

@@ -13,7 +13,6 @@
 # limitations under the License.
 
 import copy
-import itertools
 from collections import OrderedDict
 from inspect import Parameter, Signature
 from types import MappingProxyType

packages/toolbox-core/src/toolbox_core/utils.py

@@ -115,7 +115,7 @@ def params_to_pydantic_model(
         # '...' (Ellipsis) signifies a required field in Pydantic.
         # If a default value is provided in the schema, it should be used.
         default_value = ... if field.required else None
-        if field.default is not None:
+        if field.has_default:
             default_value = field.default
 
         field_definitions[field.name] = cast(

packages/toolbox-core/tests/test_protocol.py

@@ -290,6 +290,7 @@ def test_parameter_schema_map_unsupported_value_type_error():
     with pytest.raises(ValueError, match=expected_error_msg):
         schema._ParameterSchema__get_type()
 
+
 def test_parameter_schema_with_default():
     """Tests ParameterSchema with a default value provided."""
     schema = ParameterSchema(
@@ -326,3 +327,17 @@ def test_parameter_schema_required_with_default():
 
     param = schema.to_param()
     assert param.default == 3
+
+
+def test_parameter_schema_required_with_explicit_none_default():
+    """Tests explicit default=None is treated as a provided default."""
+    schema = ParameterSchema(
+        name="opt_in",
+        type="boolean",
+        description="Optional flag",
+        required=True,
+        default=None,
+    )
+
+    param = schema.to_param()
+    assert param.default is None

packages/toolbox-core/tests/test_utils.py

@@ -35,6 +35,8 @@ def create_param_mock(name: str, description: str, annotation: Type) -> Mock:
     param_mock.name = name
     param_mock.description = description
     param_mock.required = True
+    param_mock.default = None
+    param_mock.has_default = False
 
     mock_param_info = Mock()
     mock_param_info.annotation = annotation
@@ -422,6 +424,24 @@ def test_params_to_pydantic_model_with_params():
         Model(name="Bob", age="thirty", is_active=True)
 
 
+def test_params_to_pydantic_model_uses_explicit_default_none():
+    """Test that explicit default=None is honored for required schema fields."""
+    tool_name = "MyToolWithExplicitNoneDefault"
+    params = [
+        ParameterSchema(
+            name="message",
+            type="string",
+            description="Message value",
+            required=True,
+            default=None,
+        )
+    ]
+    Model = params_to_pydantic_model(tool_name, params)
+
+    assert "message" in Model.model_fields
+    assert Model.model_fields["message"].default is None
+
+
 @pytest.mark.asyncio
 async def test_resolve_value_plain_value():
     """Test resolving a plain, non-callable value."""