outlines

Generate schema-constrained JSON or typed objects from LLM prompts.

Updated Apr 9, 2026
One-click install
npx skills add https://github.com/MarbleSodas/Mavis --skill outlines-marblesodas
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: outlines
Source: https://github.com/MarbleSodas/Mavis/tree/main/optional-skills/mlops/inference/outlines
Command: npx skills add https://github.com/MarbleSodas/Mavis --skill outlines-marblesodas

SYSTEM DOCUMENTATION & REQUIREMENTS

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

What problem does it solve?

Outlines removes the pain of getting unreliable, malformed, or unvalidated model outputs by constraining generation to a precise structure so downstream code can trust the result.

Core Features & Use Cases

  • Guaranteed structured output: Generate JSON/XML/typed objects that match a schema, including Pydantic models, without guesswork.
  • Grammar-constrained decoding: Uses CFG/FSM-based token filtering to enforce valid formats at generation time.
  • Local-first & high-performance backends: Works with Transformers, llama.cpp (GGUF), and vLLM for efficient on-device or high-throughput inference.

Example use case: Extract product details from free-form text into a Pydantic model (name, price, availability) while ensuring fields and constraints (like regexes, numeric ranges, and enum values) are satisfied.

Quick Start

Ask your AI to extract entities from a document and return the result as a validated Pydantic JSON object using Outlines structured generation.

Frequently Asked Questions about outlines

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

FAQPage Schema
How do I enforce JSON schema constraints during local LLM generation?

To enforce JSON schema constraints during local LLM generation, you apply grammar-constrained decoding to filter tokens. This ensures the model output matches Pydantic models or JSON schemas for valid structured generation.

Can I use Pydantic models for structured output with vLLM?

Yes, you can use Pydantic models for structured output with vLLM. The backend supports grammar-constrained decoding to generate type-safe JSON objects that match your defined schemas during local inference.

What is the best way to extract typed objects from unstructured text using local inference?

The best way to extract typed objects from unstructured text using local inference is schema-constrained generation. It uses finite-state token filtering to guarantee outputs match your Pydantic models or regex constraints.

Does grammar-constrained decoding work with Transformers and llama.cpp backends?

Yes, grammar-constrained decoding works with Transformers and llama.cpp backends. These compatible local inference engines enforce valid JSON formats at generation time to ensure reliable structured output.

Why do I need finite-state constrained decoding for LLM information extraction?

You need finite-state constrained decoding for LLM information extraction to remove malformed or unvalidated model outputs. It enforces valid formats at generation time, ensuring downstream code can trust the extracted JSON results.