Narrow agent tool fallback to current-run items

Co-authored-by: Codex <noreply@openai.com>

Author: elainegan-openai

src/agents/agent.py

@@ -855,18 +855,25 @@ async def dispatch_stream_events() -> None:
             ):
                 return run_result.final_output
 
-            from .items import ItemHelpers
-
-            text_output = ItemHelpers.text_message_outputs(run_result.new_items)
-            if text_output:
-                return text_output
-
-            for item in reversed(run_result.to_input_list()):
-                if item.get("type") != "function_call_output":
-                    continue
-                output = item.get("output")
-                if isinstance(output, str) and output:
-                    return output
+            from .items import ItemHelpers, MessageOutputItem, ToolCallOutputItem
+
+            latest_tool_output: str | None = None
+            for item in reversed(run_result.new_items):
+                if isinstance(item, MessageOutputItem):
+                    text_output = ItemHelpers.text_message_output(item)
+                    if text_output:
+                        return text_output
+
+                if (
+                    latest_tool_output is None
+                    and isinstance(item, ToolCallOutputItem)
+                    and isinstance(item.output, str)
+                    and item.output
+                ):
+                    latest_tool_output = item.output
+
+            if latest_tool_output is not None:
+                return latest_tool_output
 
             return run_result.final_output
 

tests/test_agent_as_tool.py

@@ -30,6 +30,7 @@
     Session,
     SessionSettings,
     ToolApprovalItem,
+    ToolCallOutputItem,
     TResponseInputItem,
     Usage,
     tool_namespace,
@@ -407,6 +408,99 @@ async def extractor(result) -> str:
     assert output == "custom output"
 
 
+@pytest.mark.asyncio
+async def test_agent_as_tool_fallback_uses_current_run_items_only(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    agent = Agent(name="summarizer")
+
+    message = ResponseOutputMessage(
+        id="msg_current",
+        role="assistant",
+        status="completed",
+        type="message",
+        content=[
+            ResponseOutputText(
+                annotations=[],
+                text="Current run summary",
+                type="output_text",
+                logprobs=[],
+            )
+        ],
+    )
+
+    class DummyResult:
+        def __init__(self) -> None:
+            self.final_output = ""
+            self.new_items = [
+                ToolCallOutputItem(
+                    agent=agent,
+                    raw_item={
+                        "call_id": "call_current",
+                        "output": "Current tool output",
+                        "type": "function_call_output",
+                    },
+                    output="Current tool output",
+                ),
+                MessageOutputItem(agent=agent, raw_item=message),
+            ]
+
+        def to_input_list(self) -> list[dict[str, Any]]:
+            return [
+                {
+                    "call_id": "call_old",
+                    "output": "Old output from prior history",
+                    "type": "function_call_output",
+                }
+            ]
+
+    run_result = DummyResult()
+
+    async def fake_run(
+        cls,
+        starting_agent,
+        input,
+        *,
+        context,
+        max_turns,
+        hooks,
+        run_config,
+        previous_response_id,
+        conversation_id,
+        session,
+    ):
+        del (
+            cls,
+            starting_agent,
+            input,
+            context,
+            max_turns,
+            hooks,
+            run_config,
+            previous_response_id,
+            conversation_id,
+            session,
+        )
+        return run_result
+
+    monkeypatch.setattr(Runner, "run", classmethod(fake_run))
+
+    tool = agent.as_tool(
+        tool_name="summary_tool",
+        tool_description="Summarize current run output",
+    )
+    tool_context = ToolContext(
+        context=None,
+        tool_name="summary_tool",
+        tool_call_id="call_1",
+        tool_arguments='{"input": "hello"}',
+    )
+
+    output = await tool.on_invoke_tool(tool_context, '{"input": "hello"}')
+
+    assert output == "Current run summary"
+
+
 @pytest.mark.asyncio
 async def test_agent_as_tool_extractor_can_access_agent_tool_invocation(
     monkeypatch: pytest.MonkeyPatch,