diff --git a/packages/toolbox-core/src/toolbox_core/protocol.py b/packages/toolbox-core/src/toolbox_core/protocol.py
index 6606ef93..b101c9b8 100644
--- a/packages/toolbox-core/src/toolbox_core/protocol.py
+++ b/packages/toolbox-core/src/toolbox_core/protocol.py
@@ -42,7 +42,7 @@ def __get_type(self) -> Type:
             base_type = bool
         elif self.type == "array":
             if self.items is None:
-                raise Exception("Unexpected value: type is 'list' but items is None")
+                raise ValueError("Unexpected value: type is 'array' but items is None")
             base_type = list[self.items.__get_type()]  # type: ignore
         else:
             raise ValueError(f"Unsupported schema type: {self.type}")
diff --git a/packages/toolbox-core/tests/test_protocol.py b/packages/toolbox-core/tests/test_protocol.py
index b7650792..c2b4096d 100644
--- a/packages/toolbox-core/tests/test_protocol.py
+++ b/packages/toolbox-core/tests/test_protocol.py
@@ -86,11 +86,11 @@ def test_parameter_schema_array_no_items_error():
         name="bad_list", type="array", description="List without item type"
     )
 
-    expected_error_msg = "Unexpected value: type is 'list' but items is None"
-    with pytest.raises(Exception, match=expected_error_msg):
+    expected_error_msg = "Unexpected value: type is 'array' but items is None"
+    with pytest.raises(ValueError, match=expected_error_msg):
         schema._ParameterSchema__get_type()
 
-    with pytest.raises(Exception, match=expected_error_msg):
+    with pytest.raises(ValueError, match=expected_error_msg):
         schema.to_param()