guidance

Constrain LLM outputs with regex and grammar rules for JSON, XML, and code.

Updated Apr 30, 2026
One-click install
npx skills add https://github.com/photonics-dhl/Hermes --skill guidance-photonics-dhl
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: guidance
Source: https://github.com/photonics-dhl/Hermes/tree/main/hermes-home/skills/mlops/inference/guidance
Command: npx skills add https://github.com/photonics-dhl/Hermes --skill guidance-photonics-dhl

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

Constrained generation of outputs ensures that LLM responses are structured, validated, and machine-friendly, reducing errors and post-processing.

Core Features & Use Cases

  • Regex- and grammar-driven constraints: enforce JSON/XML/code formats and valid tokens in generation.
  • Multi-step workflows: implement pipelines with Pythonic control flow to build complex tasks.
  • Local and cloud backends: work with Guidance on transformers, llama.cpp, or API models via Guidance.
  • Real-world example: generate a user profile as a strict JSON object with fields name, age, and email, guaranteed to follow the schema.

Quick Start

Use Guidance to generate a JSON object that adheres to a strict schema.

Frequently Asked Questions about guidance

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

FAQPage Schema
How do I enforce structured LLM outputs with regex and grammars?

To enforce structured LLM outputs, you apply regex and grammar constraints during generation, guaranteeing responses follow valid JSON, XML, or code formats. This approach eliminates invalid syntax and reduces post-processing.

Can I use constrained generation for JSON with local and cloud backends?

Yes, constrained generation supports local and cloud backends. You can apply grammar-based generation features across transformers, llama.cpp, or API models to guarantee strict JSON schema adherence.

How do I build multi-step workflows for prompt engineering?

Multi-step workflows for prompt engineering are built using Pythonic control flow. You coordinate multi-step generation with validation to create complex pipelines that enforce structured outputs.

What is the best way to guarantee valid JSON generation from an LLM?

The best way to guarantee valid JSON generation is using grammar-driven constraints. By enforcing a strict schema during generation rather than post-processing, you ensure the output is always machine-friendly and validated.

Do I need Python to use the Guidance framework for constrained generation?

Yes, you need Python to use the Guidance framework. It requires Python-based workflows to coordinate multi-step generation with validation and implement grammar-driven constraints across your models.