diff --git a/litellm/main.py b/litellm/main.py
index 7d457d9cdd1..ee76f6eb190 100644
--- a/litellm/main.py
+++ b/litellm/main.py
@@ -1014,8 +1014,10 @@ def responses_api_bridge_check(
         and model_info.get("mode") != "responses"
         and OpenAIGPT5Config.is_model_gpt_5_model(model)
         and not OpenAIGPT5Config.is_model_gpt_5_search_model(model)
-        and reasoning_effort is not None
-        and (reasoning_summary is not None or (OpenAIGPT5Config.is_model_gpt_5_4_plus_model(model) and tools))
+        and (
+            (reasoning_effort is not None and reasoning_summary is not None)
+            or (OpenAIGPT5Config.is_model_gpt_5_4_plus_model(model) and tools)
+        )
     ):
         model_info["mode"] = "responses"
         model = model.replace("responses/", "")
diff --git a/tests/test_litellm/test_gpt56_bridge.py b/tests/test_litellm/test_gpt56_bridge.py
new file mode 100644
index 00000000000..bd1ac136593
--- /dev/null
+++ b/tests/test_litellm/test_gpt56_bridge.py
@@ -0,0 +1,9 @@
+"""Regression test for https://github.com/BerriAI/litellm/issues/33221"""
+from litellm.main import responses_api_bridge_check
+
+
+def test_gpt56_tools_bridged_to_responses_without_reasoning_effort():
+    tools = [{"type": "function", "function": {"name": "get_weather", "description": "Get weather", "parameters": {"type": "object", "properties": {"location": {"type": "string"}}, "required": ["location"]}}}]
+    for model in ["gpt-5.6-sol", "gpt-5.6-luna", "gpt-5.6-terra", "gpt-5.6"]:
+        model_info, _ = responses_api_bridge_check(model=model, custom_llm_provider="openai", tools=tools, reasoning_effort=None)
+        assert model_info.get("mode") == "responses", f"{model} with tools should bridge to responses even without reasoning_effort"