Stop putting the return type in with the other parameters

src/transformers/utils/chat_template_utils.py

@@ -88,18 +88,20 @@ def get_json_schema(func):
     main_doc, param_descriptions, return_doc = parse_google_format_docstring(doc)
 
     json_schema = _convert_type_hints_to_json_schema(func)
+    if (return_dict := json_schema["properties"].pop("return", None)) is not None:
+        if return_doc is not None:  # We allow a missing return docstring since most templates ignore it
+            return_dict["description"] = return_doc
     for arg in json_schema["properties"]:
-        if arg == "return":
-            if return_doc is not None:  # We allow a missing return docstring since most templates ignore it
-                json_schema["properties"][arg]["description"] = return_doc
-            continue
-        elif arg not in param_descriptions:
+        if arg not in param_descriptions:
             raise ValueError(
                 f"Cannot generate JSON schema for {func.__name__} because the docstring has no description for the argument '{arg}'"
             )
         json_schema["properties"][arg]["description"] = param_descriptions[arg]
 
-    return {"name": func.__name__, "description": main_doc, "parameters": json_schema}
+    output = {"name": func.__name__, "description": main_doc, "parameters": json_schema}
+    if return_dict is not None:
+        output["return"] = return_dict
+    return output
 
 
 def add_json_schema(func):
@@ -247,10 +249,10 @@ def _parse_type_hint(hint):
         elif origin is dict:
             # The JSON equivalent to a dict is 'object', which mandates that all keys are strings
             # However, we can specify the type of the dict values with "additionalProperties"
-            return {
-                "type": "object",
-                "additionalProperties": _parse_type_hint(get_args(hint)[1]),
-            }
+            out = {"type": "object"}
+            if len(get_args(hint)) == 2:
+                out["additionalProperties"] = _parse_type_hint(get_args(hint)[1])
+            return out
         else:
             raise ValueError("Couldn't parse this type hint, likely due to a custom class or object: ", hint)
     else: