outlines

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

1|Updated Jul 31, 2026
One-click install
npx skills add https://github.com/icyzh/hermes-web --skill outlines-icyzh
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: outlines
Source: https://github.com/icyzh/hermes-web/tree/main/optional-skills/mlops/inference/outlines
Command: npx skills add https://github.com/icyzh/hermes-web --skill outlines-icyzh

SYSTEM DOCUMENTATION & REQUIREMENTS

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

What problem does it solve?

This skill solves the issue of unreliable LLM output formats by enforcing strict structural constraints, ensuring that generated text always adheres to your required JSON, regex, or Pydantic schemas.

Core Features & Use Cases

  • Type-Safe Generation: Use Pydantic models to guarantee that LLM outputs match your application's data structures.
  • Grammar-Based Control: Constrain token sampling at the logit level to prevent invalid JSON or syntax errors.
  • Use Case: When building an automated data extraction pipeline, use this skill to ensure the model returns a perfectly formatted JSON object that can be immediately parsed by your database, eliminating the need for complex retry logic or manual cleaning.

Quick Start

Use the outlines skill to generate a structured JSON response based on the provided Pydantic model for the given prompt.

Frequently Asked Questions about outlines

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

FAQPage Schema
How do I force an LLM to generate output that strictly matches my Pydantic schema?

To force structured LLM output matching a Pydantic schema, you constrain token sampling at the logit level. This guarantees the generated text always adheres to your required JSON structure, preventing invalid syntax.

Can I use constrained sampling for structured generation with vLLM and Transformers?

Yes, you can use constrained sampling for structured generation with vLLM and Transformers. The approach supports high-throughput inference workflows across local models, ensuring type-safe and deterministic output generation in production.

What is the best way to prevent JSON syntax errors during LLM text generation?

The best way to prevent JSON syntax errors during LLM text generation is grammar-based control. By constraining token sampling at the logit level, you ensure zero-overhead, deterministic output that eliminates the need for retry logic.

How do I extract structured JSON from an LLM without manual cleaning or retries?

To extract structured JSON without manual cleaning, enforce strict structural constraints using Pydantic models or regex. This guarantees the model returns perfectly formatted JSON objects that can be immediately parsed by your database.

Does enforcing JSON schema constraints add inference overhead for local models?

No, enforcing JSON schema constraints does not add inference overhead. The process satisfies requirements for zero-overhead, type-safe, and deterministic output generation by directly manipulating token sampling probabilities.

When do I need regex or Pydantic schema constraints for LLM inference?

You need regex or Pydantic schema constraints for LLM inference when building automated data pipelines. This ensures reliable, type-safe generation for immediate database parsing, eliminating complex retry logic or manual data cleaning.