prompt-lab

Design and test LLM prompts with evaluation rubrics and test suites.

310|45|Updated Feb 22, 2026
One-click install
npx skills add https://github.com/Mathews-Tom/praxis-skills --skill prompt-lab-mathews-tom
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: prompt-lab
Source: https://github.com/Mathews-Tom/praxis-skills/tree/main/skills/prompt-lab
Command: npx skills add https://github.com/Mathews-Tom/praxis-skills --skill prompt-lab-mathews-tom

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

Replaces trial-and-error prompt iteration with a repeatable methodology that analyzes existing prompts for failure modes, generates focused variants, and produces evaluation rubrics and test suites to reliably compare prompt performance and enforce output formats.

Core Features & Use Cases

  • Prompt analysis: Identify ambiguities, missing constraints, and map prompts to known failure modes to guide targeted fixes.
  • Variant generation: Produce direct, few-shot, chain-of-thought, persona, and structured-output variants where each variant changes a single variable with hypothesis and risk notes.
  • Evaluation & testing: Design weighted rubrics, minimum five-case test suites (happy path, edge, adversarial, boundary), and format-enforcement strategies for A/B comparison across models.
  • Use case: Run prompt-lab to generate 3-4 variants and a 5-case evaluation suite to select the highest-scoring prompt for classifying support tickets or summarizing technical documents.

Quick Start

Use prompt-lab to generate two few-shot and one structured-output prompt variant plus a five-case test suite and a weighted rubric for classifying customer support tickets.

Frequently Asked Questions about prompt-lab

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

FAQPage Schema
How do I run A/B testing for LLM prompts to improve output reliability?

A/B testing for LLM prompts involves generating structured variants like few-shot or chain-of-thought, then evaluating them against weighted rubrics and test suites to reliably compare performance and enforce format compliance.

What's the best way to design a test suite for prompt evaluation across GPT-4 and Claude?

Designing a prompt evaluation test suite requires building a minimum five-case suite covering happy path, edge, adversarial, and boundary scenarios, paired with weighted rubrics for automated scoring across models like GPT-4 and Claude.

How do I analyze existing LLM prompts for failure modes and format constraints?

Analyzing existing prompts for failure modes involves identifying ambiguities, mapping to known failure patterns, and applying format-enforcement strategies to guide targeted fixes for classification or extraction tasks.

Can I use chain-of-thought and few-shot variants together for structured output generation?

Yes, generating structured output variants can combine few-shot and chain-of-thought techniques, where each variant changes a single variable and includes hypothesis and risk notes to isolate performance impacts during A/B testing.

Why does my prompt produce inconsistent results and how do I fix it with a rubric?

Inconsistent prompt results often stem from missing constraints or ambiguities; fixing them requires designing weighted evaluation rubrics and applying format constraints to systematically score and compare prompt variants.

When do I need chain-of-thought prompt engineering for multi-step reasoning tasks?

Chain-of-thought prompt engineering is needed for multi-step reasoning tasks where direct prompts fail, allowing you to generate targeted variants and evaluate them with test suites to ensure reliable format compliance.