diff --git a/contributing/samples/gepa/experiment.py b/contributing/samples/gepa/experiment.py
index 2f5d03a772..f68b349d9c 100644
--- a/contributing/samples/gepa/experiment.py
+++ b/contributing/samples/gepa/experiment.py
@@ -43,7 +43,6 @@
 from tau_bench.types import EnvRunResult
 from tau_bench.types import RunConfig
 import tau_bench_agent as tau_bench_agent_lib
-
 import utils
 
 
diff --git a/contributing/samples/gepa/run_experiment.py b/contributing/samples/gepa/run_experiment.py
index cfd850b3a3..1bc4ee58c8 100644
--- a/contributing/samples/gepa/run_experiment.py
+++ b/contributing/samples/gepa/run_experiment.py
@@ -25,7 +25,6 @@
 from absl import flags
 import experiment
 from google.genai import types
-
 import utils
 
 _OUTPUT_DIR = flags.DEFINE_string(
diff --git a/src/google/adk/auth/auth_credential.py b/src/google/adk/auth/auth_credential.py
index bc91d48f79..96b766fc3a 100644
--- a/src/google/adk/auth/auth_credential.py
+++ b/src/google/adk/auth/auth_credential.py
@@ -76,6 +76,7 @@ class OAuth2Auth(BaseModelWithConfig):
   auth_response_uri: Optional[str] = None
   auth_code: Optional[str] = None
   access_token: Optional[str] = None
+  id_token: Optional[str] = None
   refresh_token: Optional[str] = None
   expires_at: Optional[int] = None
   expires_in: Optional[int] = None
diff --git a/src/google/adk/auth/oauth2_credential_util.py b/src/google/adk/auth/oauth2_credential_util.py
index d90103a88c..b1330865c5 100644
--- a/src/google/adk/auth/oauth2_credential_util.py
+++ b/src/google/adk/auth/oauth2_credential_util.py
@@ -108,6 +108,7 @@ def update_credential_with_tokens(
   """
   auth_credential.oauth2.access_token = tokens.get("access_token")
   auth_credential.oauth2.refresh_token = tokens.get("refresh_token")
+  auth_credential.oauth2.id_token = tokens.get("id_token", None)
   auth_credential.oauth2.expires_at = (
       int(tokens.get("expires_at")) if tokens.get("expires_at") else None
   )
diff --git a/tests/unittests/auth/test_oauth2_credential_util.py b/tests/unittests/auth/test_oauth2_credential_util.py
index f1fd607ff5..e335512227 100644
--- a/tests/unittests/auth/test_oauth2_credential_util.py
+++ b/tests/unittests/auth/test_oauth2_credential_util.py
@@ -137,6 +137,7 @@ def test_update_credential_with_tokens(self):
     tokens = OAuth2Token({
         "access_token": "new_access_token",
         "refresh_token": "new_refresh_token",
+        "id_token": "some_id_token",
         "expires_at": expected_expires_at,
         "expires_in": 3600,
     })
@@ -145,5 +146,6 @@ def test_update_credential_with_tokens(self):
 
     assert credential.oauth2.access_token == "new_access_token"
     assert credential.oauth2.refresh_token == "new_refresh_token"
+    assert credential.oauth2.id_token == "some_id_token"
     assert credential.oauth2.expires_at == expected_expires_at
     assert credential.oauth2.expires_in == 3600