Structured output support for language requirements (e.g., enforce Spanish responses)

[cczw123]

Feature request: structured output for language requirement

Problem

Developers often rely on prompt instructions like "answer in Spanish", which can be unreliable and hard to validate.

Proposed solution

Add a language field in the output schema, so clients can detect/enforce the expected language.

{
  "response_language": "es",
  "answer": "..."
}

Or:

{
  "language": {"code": "es", "name": "Spanish"},
  "content": "..."
}

Example

Prompt: Explain what machine learning is. Language: Spanish

{
  "response_language": "es",
  "answer": "El aprendizaje automático es un campo de la inteligencia artificial..."
}

Benefits

• Machine-readable validation
• More reliable multilingual responses
• Easier downstream localization

Questions

Should this be part of ADK’s structured output schema and validated by the SDK?