diff --git a/agents/rag/setup_corpus.py b/agents/rag/setup_corpus.py
index 29386fa..fb94419 100644
--- a/agents/rag/setup_corpus.py
+++ b/agents/rag/setup_corpus.py
@@ -3,7 +3,7 @@
 setup_corpus.py — Create a Vertex AI RAG Engine corpus and import documents.
 Project: propane-will-491900-m5
 
-Serverless mode (RagManagedDb) — no allowlist required.
+Serverless mode is the default when no backend_config is specified.
 Region: us-central1
 """
 
@@ -31,11 +31,9 @@ def main():
             break
     else:
         print(f"Creating RAG corpus '{CORPUS_DISPLAY_NAME}' in {LOCATION} (Serverless)...")
+        # No backend_config = Serverless mode (default)
         corpus = rag.create_corpus(
             display_name=CORPUS_DISPLAY_NAME,
-            backend_config=rag.RagVectorDbConfig(
-                rag_managed_db=rag.RagManagedDb()  # Serverless — no Spanner
-            ),
         )
         print(f"Corpus created: {corpus.name}")