How would I handoff a non-reasoning model with tool calls to a reasoning model?

[maininformer]

Question

I have a non-reasoning model, gpt-4.1, that does some tool calls, and then hands off to a reasoning model, o3.

I am seeing that the server wants reasoning items with a tool call.

openai.BadRequestError: Error code: 400 - {'error': {'message': "Item 'fc_682ce5bd92248191940996c8d9a04dbb0a9f269894a5abbf' of type 'function_call' was provided without its required 'reasoning' item: 'rs_682ce5b7b5ac8191ac7a77406c8ef8780a9f269894a5abbf'.", 'type': 'invalid_request_error', 'param': 'input', 'code': None}}

I tried providing custom reasoning items during hand off using hooks, but the reasoning Id is validated; that will not work. Tried leaving the Id blank so maybe the backend will create it, also failed.

openai.NotFoundError: Error code: 404 - {'error': {'message': "Item with id 'rs_682ce817c17081919e38004aaf16b288031dc804e3dfc07c' not found.", 'type': 'invalid_request_error', 'param': 'input', 'code': None}}

I tried removing the tool call items, but then the server says no tool call results without a tool call item.

openai.BadRequestError: Error code: 400 - {'error': {'message': 'No tool call found for function call output with call_id call_4GvznfhXXkBVbpXwu2bpLjRS.', 'type': 'invalid_request_error', 'param': 'input', 'code': None}}

I do need the tool call results to be present in the context so o3 knows what happened. What do you suggest?

P.S. Switching from gpt-4.1 and o3 works great in the playground. From o3 to gpt-4.1 it does remove reasoning items, yes, but in the reverse, nothing seems to be the problem.

Many thanks.

[rm-openai]

Would you mind sharing a quick code snippet that reproduces this? Looking into it

[maininformer]

Definitely; the following will give the first error.

import asyncio, random
from dataclasses import replace
from agents import Agent, Runner, function_tool, handoff
from agents.handoffs import HandoffInputData
from agents import MessageOutputItem, ToolCallOutputItem, ToolCallItem, ReasoningItem
from openai.types.responses import ResponseOutputMessage, ResponseOutputText

# ── filter that nukes reasoning + fn‑call, keeps content as text ─────────────
def strip_reasoning_bundle(data: HandoffInputData) -> HandoffInputData:
    def transform(seq):
        cleaned = []
        for item in seq:
            if isinstance(item, ReasoningItem):
                continue
            cleaned.append(item)
        return cleaned
    return replace(
        data,
        pre_handoff_items = transform(data.pre_handoff_items),
        new_items         = transform(data.new_items),
    )

# ── tools ────────────────────────────────────────────────────────────────────
@function_tool
def make_haiku_about_haikus() -> str:
    return "\n".join([
        "Seventeen small breaths,",
        "A world folded into three,",
        "Haiku makes haiku."
    ])

@function_tool
def choose_random_word(words: list[str]) -> str:
    return random.choice(words)

# ── agent 3 ──────────────────────────────────────────────────────────────────
final_haiku_agent = Agent(
    name="Final‑Haikuist",
    model="o3",
    instructions=("The prior agent will supply ONE word. "
                  "Write a 5‑7‑5 haiku containing that word exactly once."),
)

# ── agent 2 (general model) ─────────────────────────────────────────────────
word_picker_agent = Agent(
    name="Word‑Picker",
    model="gpt-4.1",
    instructions=("Call `choose_random_word` on the list you receive, then hand off "
                  "to Final‑Haikuist; add no extra text."),
    tools=[choose_random_word],
    handoffs=[handoff(final_haiku_agent)],
)

# ── agent 1 ──────────────────────────────────────────────────────────────────
intro_haiku_agent = Agent(
    name="Intro‑Haikuist",
    model="o3",
    instructions=("Call `make_haiku_about_haikus`, then hand off to Word‑Picker."),
    tools=[make_haiku_about_haikus],
    # filter strips reasoning, fn‑call, result bundle just before the hand‑off
    handoffs=[handoff(word_picker_agent, input_filter=strip_reasoning_bundle)],
)

# ── driver ───────────────────────────────────────────────────────────────────
WORDS = ["moon", "blossom", "mountain", "breeze", "river"]

async def main() -> None:
    run = await Runner.run(intro_haiku_agent,
                           f"The candidate words are: {WORDS}")

    print(run)

if __name__ == "__main__":
    asyncio.run(main())

Since I posted, I also tried removing the function calls and converting the function call result to plain text, to pass it to the reasoning model. That also gives me a similar error as trying to add custom reasoning:

Error getting response: Error code: 404 - {'error': {'message': "Item with id 'msg_682d6cbbd7108191a2175ab5ef8a66830aab4b9647120386' not found.", 'type': 'invalid_request_error', 'param': 'input', 'code': None}}. (request_id: req_00b8858b2f83d2c46553bb4f587f9934)

[github-actions]

This issue is stale because it has been open for 7 days with no activity.

[maininformer]

This issue is stale because it has been open for 7 days with no activity.

Not stale girlie pop, I am checking this every day.

[lamaeldo]

Seconded, I am also facing this issue: it is somehow impossible to have a multi-turn conversation with the agent doing next_input = result.to_input_list() , result = await Runner.run(agent, next_input in a loop

[rm-openai]

Thanks - lost track of this, but going to try and fix today.

[rm-openai]

deployed a fix, so you shouldn't see this error any more

Reasoning input items can only be provided to a reasoning or computer use model. Remove reasoning items from your input and try again

Let me know if this resolves things or if there's more to be done!

[maininformer]

@rm-openai thank you. Just to check, does this change the behavior where non-reasoning models like gpt-4.1 would not accept reasoning items? If so that would be awesome!

Just to make sure I understand: This is the same behavior in playground, where if one switched from, say, o3 to gpt-4.1, there is a modal saying reasoning items will be removed. With your change, we would expect that that modal and behavior would be unnecessary, yes?

[rm-openai]

That's right. Reasoning items will be ignored if passed to gpt-4.1, instead of raising an error.

[maininformer]

@rm-openai Getting a 500; same snippet ^

openai.InternalServerError: Error code: 500 - {'error': {'message': 'An error occurred while processing your request. You can retry your request, or contact us through our help center at help.openai.com if the error persists. Please include the request ID req_cb60ea1236ced3875808c3a8dab3ac67 in your message.', 'type': 'server_error', 'param': None, 'code': 'server_error'}}

[rm-openai]

@maininformer ah sorry about that. Just to confirm could you run once more and just make sure you keep getting a 500 error?