const result = streamText({
    model: openai('gpt-4o'),
    messages: formattedMessages,
    tools: {
      generateImage: tool({
        description: 'Generate an image',
        parameters: z.object({
          prompt: z.string().describe('The prompt to generate the image from'),
        }),
        execute: async ({ prompt }) => {
          const { image } = await experimental_generateImage({
            model: openai.image('dall-e-3'),
            prompt,
          });
          // in production, save this image to blob storage and return a URL
          return { image: image.base64, prompt };
        },
      }),
    },
  });