diff --git a/agentkit/auth/admin.py b/agentkit/auth/admin.py
index 33c70e45..79401e5c 100644
--- a/agentkit/auth/admin.py
+++ b/agentkit/auth/admin.py
@@ -46,6 +46,12 @@
 # create sandbox sessions (the session/tool-read actions come from the custom policy).
 SANDBOX_ACCESS_POLICY = "AgentKitSandboxAccess"
 WELL_KNOWN_KEY = ".well-known/agentkit-cli"
+_TOS_BUCKET_CONFLICT_CODES = frozenset(
+    {
+        "BucketAlreadyExists",
+        "BucketAlreadyOwnedByYou",
+    }
+)
 ROLE_ACTIONS = (
     "agentkit:CreateSession", "agentkit:GetSession", "agentkit:DeleteSession",
     "agentkit:GetSessionLogs", "agentkit:SetSessionTtl",
@@ -386,9 +392,10 @@ def publish_discovery(
     client = tos.TosClientV2(ak, sk, endpoint, coords.region, security_token=token)
     try:
         client.create_bucket(bucket, acl=tos.ACLType.ACL_Public_Read)
-    except Exception as exc:  # noqa: BLE001
+    except Exception as exc:
         msg = str(exc)
-        if not any(k in msg for k in ("Exist", "exist", "Owned", "owned", "Conflict", "conflict")):
+        error_code = str(getattr(exc, "code", ""))
+        if error_code not in _TOS_BUCKET_CONFLICT_CODES:
             raise AuthError(
                 f"could not create the TOS bucket for the discovery doc: {msg[:120]}",
                 hint="enable TOS on this account and allow public-read buckets, or pass an existing bucket.",
diff --git a/tests/auth/test_admin.py b/tests/auth/test_admin.py
new file mode 100644
index 00000000..4f7d6c39
--- /dev/null
+++ b/tests/auth/test_admin.py
@@ -0,0 +1,94 @@
+# Copyright (c) 2025 Beijing Volcano Engine Technology Co., Ltd. and/or its affiliates.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import sys
+from types import SimpleNamespace
+from unittest.mock import MagicMock
+
+import pytest
+
+from agentkit.auth.admin import CliAccessCoords, publish_discovery
+from agentkit.auth.errors import AuthError
+
+
+class TosError(Exception):
+    def __init__(self, code: str, message: str):
+        super().__init__(message)
+        self.code = code
+
+
+def install_fake_tos(monkeypatch, create_bucket_error: Exception):
+    client = MagicMock()
+    client.create_bucket.side_effect = create_bucket_error
+    tos_module = SimpleNamespace(
+        ACLType=SimpleNamespace(ACL_Public_Read="public-read"),
+        TosClientV2=MagicMock(return_value=client),
+    )
+    monkeypatch.setitem(sys.modules, "tos", tos_module)
+    return client
+
+
+def make_coords() -> CliAccessCoords:
+    return CliAccessCoords(
+        account_id="account",
+        region="cn-beijing",
+        user_pool_uid="pool",
+        issuer="https://issuer.example",
+        client_id="client",
+        role_trn="role",
+        provider_trn="provider",
+    )
+
+
+@pytest.mark.parametrize(
+    "error_code",
+    ["BucketAlreadyExists", "BucketAlreadyOwnedByYou"],
+)
+def test_publish_discovery_ignores_explicit_bucket_conflicts(monkeypatch, error_code):
+    client = install_fake_tos(
+        monkeypatch,
+        TosError(error_code, "bucket is already owned"),
+    )
+
+    url = publish_discovery(
+        make_coords(),
+        bucket="existing-bucket",
+        custom_domain="agent.example",
+        access_key="ak",
+        secret_key="sk",
+    )
+
+    assert url == "https://agent.example"
+    client.put_object.assert_called_once()
+
+
+def test_publish_discovery_does_not_swallow_authentication_errors(monkeypatch):
+    client = install_fake_tos(
+        monkeypatch,
+        TosError(
+            "InvalidAccessKeyId",
+            "the specified access key does not exist",
+        ),
+    )
+
+    with pytest.raises(AuthError, match="could not create the TOS bucket"):
+        publish_discovery(
+            make_coords(),
+            bucket="new-bucket",
+            custom_domain="agent.example",
+            access_key="invalid-ak",
+            secret_key="invalid-sk",
+        )
+
+    client.put_object.assert_not_called()