outlines

Convert unstructured prompts into schema-conformant JSON outputs using Pydantic and JSON Schema.

Updated Jun 28, 2026
One-click install
npx skills add https://github.com/jleechanorg/hermes-agent --skill outlines-jleechanorg
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: outlines
Source: https://github.com/jleechanorg/hermes-agent/tree/main/optional-skills/mlops/inference/outlines
Command: npx skills add https://github.com/jleechanorg/hermes-agent --skill outlines-jleechanorg

SYSTEM DOCUMENTATION & REQUIREMENTS

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

What problem does it solve?

Outlines solves the challenge of producing strictly structured outputs from language models, ensuring generated data can be parsed reliably by JSON schemas and Pydantic models.

Core Features & Use Cases

  • Constrained generation with grammar-based rules to guarantee valid JSON-like structures.
  • Native support for Pydantic models and JSON schemas for type-safe, machine-checked results.
  • Flexible backend compatibility with local transformers, llama.cpp, vLLM, and API backends for production-grade workflows.

Quick Start

Prompt the model to generate a JSON object that strictly adheres to a Pydantic model or JSON schema.

Frequently Asked Questions about outlines

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

FAQPage Schema
How do I generate structured JSON that strictly conforms to a Pydantic model from a language model?

You can generate structured JSON conforming to a Pydantic model by applying grammar-based constrained generation to unstructured prompts, guaranteeing type-safe, machine-checked outputs that parse reliably without schema validation errors.

Does constrained JSON generation work with local models like vLLM and transformers?

Yes, constrained JSON generation supports multi-backend compatibility across local transformers, llama.cpp, and vLLM backends, ensuring production-grade workflows can produce schema-conformant JSON outputs natively across different model serving environments.

What is grammar-based generation for ensuring type-safe JSON outputs?

Grammar-based generation applies structural rules during decoding to guarantee valid JSON-like structures, converting unstructured prompts into strictly schema-conformant outputs that satisfy JSON Schema and Pydantic type-safety constraints.

Can I use JSON Schema directly for structured generation without converting to Pydantic models?

Yes, structured generation provides native support for both JSON Schema and Pydantic models, allowing you to enforce type-safe, machine-checked constraints directly from either format for reliable API payload generation and data pipelines.

What's the best way to prevent language models from generating invalid JSON for data pipelines?

The best way to prevent invalid JSON in data pipelines is using grammar-based constrained generation with zero overhead, which enforces structural rules during decoding to guarantee schema-conformant outputs natively.

Why does my language model output fail JSON schema validation during API payload generation?

Language model outputs fail JSON schema validation because unconstrained decoding produces malformed structures; applying grammar-based generation during decoding enforces strict schema-conformant JSON, eliminating parsing errors in API payload workflows.