structured-output-llm

Enforce machine-parseable JSON output from LLMs using provider-native structured output modes.

9|3|Updated Jun 13, 2026
One-click install
npx skills add https://github.com/Sir-chawakorn/sanook-cli --skill structured-output-llm
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: structured-output-llm
Source: https://github.com/Sir-chawakorn/sanook-cli/tree/main/skills/structured-output-llm
Command: npx skills add https://github.com/Sir-chawakorn/sanook-cli --skill structured-output-llm

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

This skill solves the common issue of LLMs returning malformed JSON, prose-heavy responses, or hallucinated keys when your application requires strict, predictable data structures for downstream processing.

Core Features & Use Cases

  • Provider-Enforced Schemas: Leverages native structured output modes from OpenAI, Anthropic, and Gemini to ensure 100% valid JSON.
  • Constrained Decoding: Implements grammar-level enforcement for open-weights models to make invalid output structurally impossible.
  • Robust Validation: Provides a backstop repair-and-retry loop using Pydantic or Zod to handle edge cases like truncation or refusals.
  • Use Case: Automatically extract invoice data into a database or classify customer support tickets into fixed categories without ever breaking your JSON parser.

Quick Start

Use the structured-output-llm skill to define a Pydantic model for your data and force the LLM to return a strictly validated JSON object matching that schema.

Frequently Asked Questions about structured-output-llm

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I force an LLM to return valid JSON matching my Pydantic schema?

You force valid JSON from an LLM by utilizing provider-native structured output modes and constrained decoding grammars. This guarantees machine-parseable responses matching your Pydantic schema, preventing malformed JSON or hallucinated keys in downstream processing.

What is constrained decoding for structured output and when do I need it?

Constrained decoding enforces grammar-level rules on open-weights models, making invalid JSON structurally impossible. You need it for automated data extraction or classification workflows where strict schema adherence is critical and malformed responses would break your parser.

Does this approach to structured LLM output work with Zod and TypeScript?

Yes, structured output validation works with Zod alongside Pydantic. It uses these typed validation libraries as a backstop repair-and-retry loop to handle edge cases like truncation or refusals, ensuring data integrity across your application stack.

How do I handle LLM parsing failures and truncated JSON responses?

To handle LLM parsing failures, the structured output approach implements a robust validation backstop using Pydantic or Zod. This automatically triggers a repair-and-retry loop for edge cases like truncation or refusals to ensure schema adherence.

Can I use structured output modes with OpenAI, Anthropic, and Gemini models?

Yes, you can use structured output modes with OpenAI, Anthropic, and Gemini. The skill leverages these provider-enforced native modes to ensure 100% valid JSON output for automated data extraction, classification, and function-calling workflows.