Claude API - Structured Outputs & Error Prevention Guide

Package: @anthropic-ai/sdk@0.71.2 Breaking Changes: Oct 2025 - Claude 3.5/3.7 models retired, Nov 2025 - Structured outputs beta Last Updated: 2026-01-09

What's New in v0.69.0+ (Nov 2025)

Major Features:

1. Structured Outputs (v0.69.0, Nov 14, 2025) - CRITICAL ⭐

Guaranteed JSON schema conformance - Claude's responses strictly follow your JSON schema with two modes.

⚠️ ACCURACY CAVEAT: Structured outputs guarantee format compliance, NOT accuracy. Models can still hallucinate—you get "perfectly formatted incorrect answers." Always validate semantic correctness (see below).

JSON Outputs (output_format) - For data extraction and formatting: