diff --git a/test/examples/ai_powered_decorator/gen_user_info.py b/test/examples/ai_powered_decorator/gen_user_info.py
index fa8943e..eacd7ca 100644
--- a/test/examples/ai_powered_decorator/gen_user_info.py
+++ b/test/examples/ai_powered_decorator/gen_user_info.py
@@ -10,6 +10,7 @@ class UserInfo:
 
 @ai_powered
 def gen_user_info() -> UserInfo:
+    ''' ramdomly generate user info for testing, None is used for unknown fields '''
     ...
 
 @ai_powered
diff --git a/test/json_schema/annotated.py b/test/json_schema/annotated.py
new file mode 100644
index 0000000..963e3cc
--- /dev/null
+++ b/test/json_schema/annotated.py
@@ -0,0 +1,18 @@
+import json
+import msgspec
+from typing_extensions import Annotated
+from pydantic.dataclasses import dataclass
+from typing import Optional
+
+from ai_powered.schema_deref import deref
+
+@dataclass
+class UserInfo:
+    name: str
+    country: Annotated[Optional[str], "None is used for unknown cases"]
+    age: Annotated[Optional[str], "None is used for unknown cases"]
+
+if __name__ == "__main__":
+    schema = msgspec.json.schema(UserInfo)
+    print("schema =", json.dumps(schema, indent=2))
+    print("deref(schema) =", json.dumps(deref(schema), indent=2))