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Anthropic

Claude supports structured output via tool use. Pass DOCUMENT_SCHEMA as a tool’s input_schema and force the model to use it with tool_choice. 
from surfacedocs import SurfaceDocs, DOCUMENT_SCHEMA, SYSTEM_PROMPT
import anthropic

client = anthropic.Anthropic()
docs = SurfaceDocs()

response = client.messages.create(
    model="claude-sonnet-4-20250514",
    max_tokens=4096,
    system=SYSTEM_PROMPT,
    messages=[
        {"role": "user", "content": "Write documentation for user authentication"},
    ],
    tools=[{
        "name": "create_document",
        "description": "Create a structured document",
        "input_schema": DOCUMENT_SCHEMA,
    }],
    tool_choice={"type": "tool", "name": "create_document"},
)

# Extract the tool use block
tool_use = next(b for b in response.content if b.type == "tool_use")
result = docs.save(tool_use.input)
print(f"Saved: {result.url}")
Claude doesn’t have a native response_format like OpenAI. Instead, we use tool use to enforce the schema. Setting tool_choice to the specific tool name guarantees Claude will output in the correct format.

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How it works

  1. SYSTEM_PROMPT tells Claude about the document format
  2. DOCUMENT_SCHEMA is passed as a tool’s input schema
  3. tool_choice forces Claude to call the tool (guaranteeing structured output)
  4. The tool use block’s input contains the document data
  5. Pass it directly to docs.save()