OpenAI has enhanced its Structured Outputs feature by introducing support for parallel function calling in strict mode, which ensures that function calls consistently adhere to predefined schemas. The update also expands the range of supported keywords, allowing developers to specify output string lengths and formats using regular expressions and formats such as email. These improvements incorporate additional features from JSON Schema, including value ranges and error handling for parallel function calls. The enhancements have been acknowledged by developers and the llguidance team, highlighting the increased precision and flexibility in API responses.