diff --git a/src/google/adk/flows/llm_flows/tools/_toolset_auth.py b/src/google/adk/flows/llm_flows/tools/_toolset_auth.py
index 5c0d7e57da..a3c03c8b0d 100644
--- a/src/google/adk/flows/llm_flows/tools/_toolset_auth.py
+++ b/src/google/adk/flows/llm_flows/tools/_toolset_auth.py
@@ -24,7 +24,6 @@
 
 from ....agents.callback_context import CallbackContext
 from ....agents.invocation_context import InvocationContext
-from ....auth.auth_preprocessor import TOOLSET_AUTH_CREDENTIAL_ID_PREFIX
 from ....auth.auth_tool import AuthConfig
 from ....events.event import Event
 from ....models.llm_request import LlmRequest
@@ -96,6 +95,8 @@ async def resolve_toolset_auth(
       invocation_context.credential_by_key[credential_key] = credential
     else:
       # Need auth - will interrupt
+      from ....auth.auth_preprocessor import TOOLSET_AUTH_CREDENTIAL_ID_PREFIX
+
       toolset_id = (
           f'{TOOLSET_AUTH_CREDENTIAL_ID_PREFIX}{type(tool_union).__name__}'
       )