diff --git a/src/neuroconv/utils/json_schema.py b/src/neuroconv/utils/json_schema.py
index 6aa7a75d0..a7e6e0518 100644
--- a/src/neuroconv/utils/json_schema.py
+++ b/src/neuroconv/utils/json_schema.py
@@ -140,7 +140,8 @@ def get_json_schema_from_method_signature(method: Callable, exclude: Optional[li
             additional_properties = True
             continue
 
-        annotation = parameter.annotation
+        # If no annotation is provided (inspect._empty), use Any instead
+        annotation = Any if parameter.annotation is inspect._empty else parameter.annotation
 
         # Pydantic uses ellipsis for required
         pydantic_default = ... if parameter.default is inspect._empty else parameter.default
diff --git a/tests/test_minimal/test_utils/test_get_json_schema_from_method_signature.py b/tests/test_minimal/test_utils/test_get_json_schema_from_method_signature.py
index e6fe27e16..c2cea1d75 100644
--- a/tests/test_minimal/test_utils/test_get_json_schema_from_method_signature.py
+++ b/tests/test_minimal/test_utils/test_get_json_schema_from_method_signature.py
@@ -424,3 +424,26 @@ def test_class_method(self, integer: int):
     }
 
     assert test_json_schema == expected_json_schema
+
+
+def test_get_json_schema_from_method_signature_unannotated():
+    """Test that parameters without type annotations are handled correctly by defaulting to Any."""
+
+    def method_with_unannotated_params(
+        annotated_param: int, unannotated_param, unannotated_with_default="default_value"
+    ):
+        pass
+
+    test_json_schema = get_json_schema_from_method_signature(method=method_with_unannotated_params)
+    expected_json_schema = {
+        "additionalProperties": False,
+        "properties": {
+            "annotated_param": {"type": "integer"},
+            "unannotated_param": {},  # Any type in JSON Schema is represented by an empty object
+            "unannotated_with_default": {"default": "default_value"},
+        },
+        "required": ["annotated_param", "unannotated_param"],
+        "type": "object",
+    }
+
+    assert test_json_schema == expected_json_schema