Not connecting with Anthropic API for picture description

[paulohss]

Hi all!

I'm trying to use Claude Sonnet to add descriptions to the images on PDFs with the following code:

api_key = "sk-ant-api03-YOUR_ACTUAL_KEY_HERE"
model = "claude-sonnet-4-5-20250929"

picture_desc_api_option = PictureDescriptionApiOptions(
    url="https://api.anthropic.com/v1/messages",
    prompt="Describe this image in sentences in a single paragraph.",
    params=dict(
        model=model,
        max_tokens=1024,
        messages=[],  # Docling might need this structure
    ),
    headers={
        "x-api-key": api_key,
        "anthropic-version": "2023-06-01",
        "Content-Type": "application/json",
    },
    timeout=60,
)

When I run, it gives this error:
HTTPError: 400 Client Error: Bad Request for url: https://api.anthropic.com/v1/messages

According to Anthropic:
A 400 Bad Request error means the API request format is incorrect. This is likely because Docling is formatting the request in a way that doesn't match Anthropic's API expectations, for example:

• Missing required fields: Anthropic's API requires specific fields like the messages array
• Image encoding: The image data might not be formatted correctly
• Docling compatibility: Docling might be designed for OpenAI's format, not Anthropic's