What you will learn In this playbook, you will learn how to test whether an AI Skill genuinely improves an AI model’s performance. You will compare the same task in two conditions: Test A: The AI completes the task without the Skill. Test B: The AI completes the task with the Skill. You will then evaluate both results using clear criteria rather than relying on which answer simply “looks better”. Who this playbook is for This playbook is suitable for beginners who: Use ChatGPT, Claude, Gemini or another AI assistant. Create reusable prompts, Custom GPT instructions, Gems or Agent Skills. Want more consistent AI results. Need a simple way to test whether their instructions are working. Want to improve an AI workflow without guessing. You do not need coding experience. Estimated time: Approximately 35 to 50 minutes. Level: Beginner Tools you will need: Choose one AI assistant: ChatGPT Claude Gemini Microsoft Copilot Another text-based AI assistant You will also need somewhere to record your results: A Word or Google document A spreadsheet A notes application The evaluation table included in this playbook For the beginner activity, you do not need to install any software. An optional advanced activity later in the playbook introduces the open-source agent-skills-eval project. 1. What is an AI Skill? An AI Skill is a reusable set of instructions, examples, rules and resources that helps an AI perform a specific task. A Skill might teach an AI how to: Review a CV. Analyse a spreadsheet. Write a lesson plan. Assess learner work. Research a topic. Create a presentation. Review another AI agent’s code. Produce a report using a required format. A Skill may be stored in different ways. For example: Custom instructions A Custom GPT A Gemini Gem A saved master prompt A SKILL.md file A reusable workflow inside an AI application The important idea is that the Skill should provide more than a one-time prompt. It should give the AI a consistent method to follow.