diff --git a/src/google/adk/tools/openapi_tool/auth/credential_exchangers/oauth2_exchanger.py b/src/google/adk/tools/openapi_tool/auth/credential_exchangers/oauth2_exchanger.py
index 91f3909672b..f8e2097efb3 100644
--- a/src/google/adk/tools/openapi_tool/auth/credential_exchangers/oauth2_exchanger.py
+++ b/src/google/adk/tools/openapi_tool/auth/credential_exchangers/oauth2_exchanger.py
@@ -104,6 +104,7 @@ def exchange_credential(
         ValueError: If the auth scheme or auth credential is invalid.
     """
     # TODO(cheliu): Implement token refresh flow
+    # Note: Token refresh should handle expired access tokens gracefully
 
     self._check_scheme_credential_type(auth_scheme, auth_credential)