diff --git a/run_agent.py b/run_agent.py
index 57e2a13ba7..9b3a7dba35 100644
--- a/run_agent.py
+++ b/run_agent.py
@@ -2340,7 +2340,10 @@ class AIAgent:
                 "instructions": instructions,
                 "input": self._chat_messages_to_responses_input(payload_messages),
                 "tools": self._responses_tools(),
+                "tool_choice": "auto",
+                "parallel_tool_calls": True,
                 "store": False,
+                "prompt_cache_key": self.session_id,
             }
 
             if reasoning_enabled:
diff --git a/tests/test_run_agent_codex_responses.py b/tests/test_run_agent_codex_responses.py
index a1e5e817e0..cf2694f098 100644
--- a/tests/test_run_agent_codex_responses.py
+++ b/tests/test_run_agent_codex_responses.py
@@ -235,6 +235,10 @@ def test_build_api_kwargs_codex(monkeypatch):
     assert kwargs["tools"][0]["strict"] is False
     assert "function" not in kwargs["tools"][0]
     assert kwargs["store"] is False
+    assert kwargs["tool_choice"] == "auto"
+    assert kwargs["parallel_tool_calls"] is True
+    assert isinstance(kwargs["prompt_cache_key"], str)
+    assert len(kwargs["prompt_cache_key"]) > 0
     assert "timeout" not in kwargs
     assert "max_tokens" not in kwargs
     assert "extra_body" not in kwargs