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Default Models

gpt_5_reasoning_settings_required 

gpt_5_reasoning_settings_required(model_name: str) -> bool

Returns True if the model name is a GPT-5 model and reasoning settings are required.

Source code in src/agents/models/default_models.py 
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def gpt_5_reasoning_settings_required(model_name: str) -> bool:
    """
    Returns True if the model name is a GPT-5 model and reasoning settings are required.
    """
    if model_name.startswith("gpt-5-chat"):
        # gpt-5-chat-latest does not require reasoning settings
        return False
    # matches any of gpt-5 models
    return model_name.startswith("gpt-5")

is_gpt_5_default 

is_gpt_5_default() -> bool

Returns True if the default model is a GPT-5 model. This is used to determine if the default model settings are compatible with GPT-5 models. If the default model is not a GPT-5 model, the model settings are compatible with other models.

Source code in src/agents/models/default_models.py 
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def is_gpt_5_default() -> bool:
    """
    Returns True if the default model is a GPT-5 model.
    This is used to determine if the default model settings are compatible with GPT-5 models.
    If the default model is not a GPT-5 model, the model settings are compatible with other models.
    """
    return gpt_5_reasoning_settings_required(get_default_model())

get_default_model 

get_default_model() -> str

Returns the default model name.

Source code in src/agents/models/default_models.py 
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def get_default_model() -> str:
    """
    Returns the default model name.
    """
    return os.getenv(OPENAI_DEFAULT_MODEL_ENV_VARIABLE_NAME, "gpt-4.1").lower()

get_default_model_settings 

get_default_model_settings(
    model: Optional[str] = None,
) -> ModelSettings

Returns the default model settings. If the default model is a GPT-5 model, returns the GPT-5 default model settings. Otherwise, returns the legacy default model settings.

Source code in src/agents/models/default_models.py 
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def get_default_model_settings(model: Optional[str] = None) -> ModelSettings:
    """
    Returns the default model settings.
    If the default model is a GPT-5 model, returns the GPT-5 default model settings.
    Otherwise, returns the legacy default model settings.
    """
    _model = model if model is not None else get_default_model()
    if gpt_5_reasoning_settings_required(_model):
        return copy.deepcopy(_GPT_5_DEFAULT_MODEL_SETTINGS)
    return ModelSettings()