outlines

Constrain token sampling with schema-derived grammars for valid JSON/XML outputs.

Updated May 2, 2026
One-click install
npx skills add https://github.com/qcmuu/AI-Research-Skills --skill outlines-qcmuu
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: outlines
Source: https://github.com/qcmuu/AI-Research-Skills/tree/main/16-prompt-engineering/outlines
Command: npx skills add https://github.com/qcmuu/AI-Research-Skills --skill outlines-qcmuu

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill requires outlines, transformers, vllm, pydantic, and includes references (resource) components.

What problem does it solve?

This Skill prevents malformed model outputs by constraining generation to valid JSON/XML/code structures, so downstream parsing and integrations stop failing.

Core Features & Use Cases

  • Guaranteed structured outputs: Enforce valid JSON/XML (and schema-constrained text) during generation rather than validating after the fact.
  • Type-safe Pydantic workflows: Generate directly into Pydantic models for consistent, strongly-typed results.
  • Fast, local-capable backends: Use local Transformers, llama.cpp, or high-throughput vLLM to keep latency low and throughput high.
  • Schema/grammar-level control: Convert JSON schemas or Pydantic models into grammars/finite-state machines to constrain tokens.

Quick Start

Use the outlines skill to generate a Pydantic model instance that matches your desired JSON structure from your prompt.

Frequently Asked Questions about outlines

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

FAQPage Schema
How do I guarantee valid JSON generation from a local LLM?▼

This Skill enforces valid JSON generation by converting Pydantic models or JSON schemas into finite-state machines that constrain token sampling, ensuring downstream parsing never fails.

Can I use Pydantic models to generate structured responses with vLLM?▼

Yes, you can generate directly into Pydantic models using vLLM. The tool converts your Pydantic schemas into grammars to constrain token sampling, ensuring type-safe, deterministic validity.

How does grammar-based decoding prevent malformed LLM outputs?▼

Grammar-based decoding prevents malformed outputs by converting JSON schemas into finite-state machines that restrict token sampling to valid structures, eliminating parsing errors before text generation.

Does structured generation work with local Transformers and llama.cpp backends?▼

Yes, structured generation works with local Transformers and llama.cpp backends. It applies schema-derived constraints to these local environments to keep latency low and throughput high.

What is the best way to extract structured data from unstructured text using a local LLM?▼

The best way to extract structured data is to define a Pydantic model or JSON schema and use grammar-based decoding to constrain the local LLM output into that exact valid structure.

Why does my LLM output invalid JSON when I request structured data?▼

LLMs output invalid JSON because token sampling is unconstrained. You need grammar-based decoding to restrict generation to valid structures, ensuring downstream parsing succeeds.