Getting Claude to return well-formed JSON or structured data reliably is critical for production applications.

Best Practices

• Specify the exact JSON schema you want in the prompt
• Provide an example of the desired output structure
• Ask Claude to respond with ONLY the JSON, no prose
• Use tool use / function calling for guaranteed schema adherence

Example Prompt Ending

Respond with only valid JSON matching this schema:
{"name": string, "score": number}

Reference:

Structured outputs documentation

https://docs.anthropic.com/en/docs/build-with-claude/structured-outputs