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.