Constrain output with a JSON Schema

response = client.messages.create(
    model="claude-opus-5-5",
    max_tokens=16000,
    messages=[{"role": "user", "content": "Extract the name from: John Smith wants the Enterprise plan."}],
    output_config={"format": {"type": "json_schema", "schema": {
        "type": "object",
        "properties": {"name": {"type": "string"}},
        "required": ["name"],
        "additionalProperties": False,
    }}},
)