fix(core): require all nested properties for strict tool schemas

[Nishitha M (imnishitha)]

Closes #33869, #38223

Issue:

OpenAI strict tool schemas fail when nested objects contain properties that are optional

class Filters(BaseModel):
    category: str | None = None
    active: bool | None = None


class Ingredient(BaseModel):
    name: str
    amount: int
    filters: Filters | None = None


class Recipe(BaseModel):
    ingredients: list[Ingredient]


my_tool = convert_to_openai_tool(Recipe, strict=True)

model = init_chat_model("openai:gpt-5.4", use_responses_api=True)
response = model.bind_tools([my_tool], strict=True).invoke("Give me a recipe for Banana pudding. It should have 3 ingredients. Call the tool.")

Throws:

Output:

openai.BadRequestError: Error code: 400 - {'error': {'message': "Invalid schema for function 'browser_console_messages': In context=(), 'required' is required to be supplied and to be an array including every key in properties. Missing 'onlyErrors'.", 'type': 'invalid_request_error', 'param': 'tools[2].function.parameters', 'code': 'invalid_function_parameters'}}
During task with name 'model' and id '708d0a1a-0bb5-1d86-e7d7-b37d6e41009a'

Fix:

convert_to_openai_function(strict=True) now recursively adds all object properties to required, matching OpenAI's strict schema requirements.

[codspeed-hq]

Merging this PR will not alter performance

✅ 15 untouched benchmarks
⏩ 2 skipped benchmarks¹

---

_{Comparing imnishitha/core/strict-nested-required (3d6ae7c) with master (94509fa)²}

Footnotes

1. 2 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on master (32c15bb) during the generation of this report, so 94509fa was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[open-swe]

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[Sydney Runkle (sydney-runkle)]

left a few questions, thanks!

[Sydney Runkle (sydney-runkle)]

why $defs and definitions?

[Sydney Runkle (sydney-runkle)]

should we instead be rejecting these tools then?
ccurme (@ccurme) are we in agreement that we should be mutating schemas?