Python: Fix bool parameter coercion so string "false" is not silently treated as True

python/semantic_kernel/functions/kernel_function_from_method.py

@@ -139,6 +139,14 @@ def _parse_parameter(self, value: Any, param_type: Any) -> Any:
                 item_type = param_type.__args__[0]
                 return [self._parse_parameter(item, item_type) for item in value]
             raise FunctionExecutionException(f"Expected a list for {param_type}, but got {type(value)}")
+        elif param_type is bool and isinstance(value, str):
+            # bool("false") is True for any non-empty string, so parse the string explicitly.
+            lowered = value.strip().lower()
+            if lowered in ("true", "1"):
+                return True
+            if lowered in ("false", "0"):
+                return False
+            raise FunctionExecutionException(f"Cannot parse string '{value}' as bool.")
         else:
             try:
                 if isinstance(value, dict) and hasattr(param_type, "__init__"):

python/tests/unit/functions/test_kernel_function_from_method.py

@@ -520,6 +520,49 @@ def test_parse_invalid_list_raises_exception(get_custom_type_function_pydantic):
         func._parse_parameter(value, param_type)
 
 
+@pytest.mark.parametrize(
+    ("value", "expected"),
+    [
+        ("true", True),
+        ("True", True),
+        ("1", True),
+        ("false", False),
+        ("False", False),
+        ("FALSE", False),
+        ("0", False),
+        (" false ", False),
+        (True, True),
+        (False, False),
+        (1, True),
+        (0, False),
+    ],
+)
+def test_parse_bool_parameter(get_custom_type_function_pydantic, value, expected):
+    func = get_custom_type_function_pydantic
+    result = func._parse_parameter(value, bool)
+    assert result is expected
+
+
+def test_parse_invalid_bool_string_raises_exception(get_custom_type_function_pydantic):
+    func = get_custom_type_function_pydantic
+    with pytest.raises(FunctionExecutionException, match=r"Cannot parse string 'yes' as bool."):
+        func._parse_parameter("yes", bool)
+
+
+async def test_bool_parameter_from_string_argument(kernel: Kernel):
+    @kernel_function
+    def func_bool(enabled: bool) -> str:
+        return f"enabled={enabled}"
+
+    func = kernel.add_function(plugin_name="test", function_name="func_bool", function=func_bool)
+
+    res = await kernel.invoke(func, KernelArguments(enabled="false"))
+    assert str(res) == "enabled=False"
+
+    res = await kernel.invoke(func, KernelArguments(enabled="true"))
+    assert str(res) == "enabled=True"
+
+
 def test_parse_dict_with_init_non_pydantic(get_custom_type_function_nonpydantic):
     func = get_custom_type_function_nonpydantic
     value = {"id": "3", "name": "Alice"}