Gemini native format

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Gemini content generation (native format)

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Basics

• Endpoint: POST /v1beta/models/{model}:generateContent/
• Path: model — e.g. gemini-3-pro-image-preview.
• Auth: Bearer Token
• Content-Type: application/json

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Request body

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Response

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Example (image)

{
  "contents": [
    {
      "role": "user",
      "parts": [
        {
          "text": "draw a futuristic city at sunset"
        }
      ]
    }
  ],
  "generationConfig": {
    "responseModalities": ["TEXT", "IMAGE"],
    "imageConfig": {
      "aspectRatio": "16:9",
      "imageSize": "4K"
    },
    "thinkingConfig": {
      "includeThoughts": true
    }
  }
}

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Tips

1. Thoughts: includeThoughts: true surfaces how the model interprets the prompt—useful for debugging complex prompts.
2. Multimodal: With both TEXT and IMAGE, you often get explanatory text then the image.
3. Model id: Ensure {model} matches what your key can access.