outlines

Generate JSON, Pydantic models, and regex via CFG/FSM constrained decoding.

Updated Apr 20, 2026
One-click install
npx skills add https://github.com/matthew-johnson/hermes-agent --skill outlines-matthew-johnson
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: outlines
Source: https://github.com/matthew-johnson/hermes-agent/tree/main/skills/mlops/inference/outlines
Command: npx skills add https://github.com/matthew-johnson/hermes-agent --skill outlines-matthew-johnson

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

Outlines provides deterministic, structure-constrained generation that guarantees JSON, Pydantic, and regex outputs, enabling safer data contracts between AI prompts and downstream systems.

Core Features & Use Cases

  • Constrained generation using CFG/FSM to produce valid JSON, Pydantic models, or regex patterns.
  • Native Pydantic integration for strict typing and automatic schema validation.
  • Local-backend friendly: supports Transformers, llama.cpp, and vLLM for zero-overhead inference.
  • Use cases include data extraction, form processing, and production-grade structured-generation pipelines.

Quick Start

Load a local model and generate a structured JSON output from a natural language 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 language model?

To guarantee valid JSON generation from local models, you can apply CFG/FSM constraints during inference. This enforces structured generation rules, ensuring outputs strictly match your required JSON schema without processing overhead.

How does Pydantic integration work for structured generation in local inference?

Pydantic integration for structured generation uses native schema validation to enforce strict typing. It constrains local model outputs to automatically match your Pydantic models, guaranteeing that generated text validates against your data contracts.

Can I use constrained generation with llama.cpp, vLLM, and Transformers backends?

Yes, constrained generation supports multi-backend local inference across llama.cpp, vLLM, and Transformers. This provides zero-overhead structured generation across different local model environments, ensuring valid JSON or Pydantic outputs.

What is the best way to extract structured data from unstructured text using local models?

The best way to extract structured data is using grammar-based generation constraints. By applying regex or Pydantic schemas to local model inference, you deterministically extract and validate data without risking malformed outputs.

Why does my local model produce invalid JSON when generating structured outputs?

Local models produce invalid JSON because unconstrained generation lacks schema enforcement. Applying FSM or CFG constraints during inference restricts the token sampling space, forcing the model to only generate valid JSON or Pydantic structures.

Are there limitations when using regex patterns for structured generation?

Regex patterns for structured generation constrain outputs to exact pattern matches, which limits creative text generation. This approach is best suited for strict data extraction and form processing where deterministic, pattern-validated outputs are required.