outlines

Constrain LLM token sampling to JSON schemas, regex patterns, or Pydantic models.

Updated Jul 13, 2026
One-click install
npx skills add https://github.com/zangjeicy/Hermes --skill outlines-zangjeicy
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: outlines
Source: https://github.com/zangjeicy/Hermes/tree/main/optional-skills/mlops/inference/outlines
Command: npx skills add https://github.com/zangjeicy/Hermes --skill outlines-zangjeicy

SYSTEM DOCUMENTATION & REQUIREMENTS

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

What problem does it solve?

This skill solves the common issue of LLMs producing inconsistent or invalid output formats, ensuring that generated text strictly adheres to required JSON, regex, or Pydantic schemas.

Core Features & Use Cases

  • Type-Safe Generation: Uses Pydantic models to enforce strict data structures during the token generation process.
  • Grammar-Based Constraints: Employs Finite State Machines to filter tokens at the logit level, making invalid output impossible.
  • Use Case: Ideal for building robust data extraction pipelines where you need to guarantee that an LLM returns a valid JSON object matching a specific schema for downstream database insertion.

Quick Start

Use the outlines skill to generate a structured JSON object from the provided text using the User Pydantic model.

Frequently Asked Questions about outlines

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

FAQPage Schema
How do I guarantee structured JSON output from an LLM?

To guarantee structured JSON output, you must constrain LLM token sampling using Finite State Machines. This filters logits at the generation level, making invalid JSON or schema violations impossible during inference.

How does structured generation enforce Pydantic models during text generation?

Structured generation enforces Pydantic models by applying grammar-based constraints via Finite State Machines. It filters tokens at the logit level during generation, ensuring the output strictly matches your defined data structures.

Does structured generation work with vLLM and Transformers?

Yes, structured generation supports high-throughput inference backends including vLLM, Transformers, and llama.cpp. This ensures zero-overhead, type-safe, and deterministic output generation in local model environments.

What is the best way to extract data using regex patterns and LLMs?

The best way to extract data using regex patterns is to constrain token sampling to specific regex schemas. This enforces deterministic output generation, ensuring the LLM returns valid text matching your exact pattern requirements.

Can I use Pydantic models to enforce type-safe data extraction pipelines?

Yes, you can use Pydantic models to enforce strict data structures during the token generation process. This guarantees the LLM returns a valid JSON object matching your schema for downstream database insertion.

Are there limitations to constraining token sampling for structured generation?

Constraining token sampling requires compatible local model environments and inference backends like vLLM or Transformers. It is strictly for type-safe, deterministic output generation and requires predefined JSON, regex, or Pydantic schemas.