fix: reject non-object function tool input JSON#3166
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seratch merged 1 commit intoopenai:mainfrom May 7, 2026
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Mirror the MCP fix in openai#3135 for the function-tool path: when the model emits a JSON array or scalar instead of an object, `**unpack` into the pydantic params model raises a TypeError that is not matched by `_extract_tool_argument_json_error`, so the ModelBehaviorError-based retry path is bypassed. Validate the parsed shape and raise a ModelBehaviorError with a clear message instead.
seratch
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LGTM; we can merge once Codex says 👍
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@codex review now |
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@codex review |
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Codex Review: Didn't find any major issues. Already looking forward to the next diff. ℹ️ About Codex in GitHubYour team has set up Codex to review pull requests in this repo. Reviews are triggered when you
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Summary
Mirror the MCP fix in #3135 for the function-tool path. When the model emits a JSON array or scalar (e.g.
[1, 2, 3],"foo",null) instead of an object as tool arguments,**unpackinto the pydantic params model raises a rawTypeError. ThatTypeErroris not matched by_extract_tool_argument_json_error(which only matchesModelBehaviorErrorwhose message starts with"Invalid JSON input for tool"), so thedefault_tool_error_function"please try again with valid JSON" retry path is bypassed and the run fails with a confusing error instead of asking the model to fix its arguments.This validates the parsed JSON shape inside
_parse_function_tool_json_inputand raises a cleanModelBehaviorErrorfor non-object input, matching the MCP precedent. Affects both the standard runtime tool path and the realtime tool path (both reach the same parser).Test plan
test_function_tool_rejects_non_object_json_inputcovering JSON arrays, strings, numbers, null, and bool — each must raiseModelBehaviorErrorwith"expected a JSON object".uv run pytest tests/test_function_tool.py tests/test_run_step_execution.py tests/test_function_tool_decorator.py tests/test_agent_as_tool.py— 191 passed.uv run ruff check src/agents/tool.py tests/test_function_tool.py— All checks passed.Issue number
N/A — found while reviewing function-tool error handling consistency with #3135.
Checks
make lintandmake format