user-centered-design-skill

User-Centered Design Skill

An operational User-Centered Design (UCD) skill for AI coding and assistant platforms such as Codex, Claude, and other agents that support reusable skills, instructions, or custom context files. It helps the agent diagnose product design problems, choose the right UCD framework, and return practical recommendations instead of abstract theory.

Use it when you want the assistant to act like a product design consultant: asking for the right context, analyzing user flows, applying design principles, planning usability research, creating personas, or evaluating an interface.

What This Skill Does

This skill turns UCD concepts into a repeatable workflow:

1. Gather the product, user, task, pain point, mental model, and constraints.
2. Diagnose the problem through four UCD pillars:
   • Visibility
   • Feedback
   • Mental model
   • Cognitive load
3. Select the right framework for the situation.
4. Deliver a concrete artifact, such as an audit, design recommendation, persona, usability study plan, or journey map.

The goal is not to make the assistant explain design theory. The goal is to make it apply UCD thinking to real product decisions.

When To Use It

Use this skill for tasks like:

• Reviewing a confusing interface
• Improving visual hierarchy and visibility
• Reducing cognitive load in complex flows
• Applying Gestalt principles, Hick's Law, or Fitt's Law
• Designing onboarding flows
• Creating personas and user scenarios
• Planning usability studies
• Running heuristic evaluations
• Defining UX goals for a product or feature
• Prioritizing interface changes based on user behavior

Example Prompts

Use the user-centered-design skill to audit this checkout flow.

I am designing an onboarding flow for a finance app. Help me reduce drop-off using UCD principles.

Create personas and usage scenarios for a dashboard used by non-technical operations managers.

Evaluate this screen using Nielsen's heuristics and classify each issue by severity.

Help me plan a usability study for a prototype. I need tasks, success metrics, and interview questions.

Included Frameworks

The skill includes guidance for:

• UCD diagnostic workflow
• Visibility, feedback, mental models, and cognitive load
• Gestalt principles, especially proximity and visual grouping
• Visual hierarchy and prominence
• Progressive disclosure
• Affordance and constraints
• Hick's Law
• Fitt's Law
• Personas and scenarios
• User research methods
• Usability studies
• Nielsen's 10 usability heuristics
• Iterative design cycles

The detailed reference material lives in references/ucd-frameworks.md.

Repository Structure

.
|-- SKILL.md
|-- README.md
`-- references/
    `-- ucd-frameworks.md

Compatibility

This skill is designed to be platform-friendly. You can use it with:

• Codex skills
• Claude skills or custom instructions
• Other AI assistants that support reusable instruction files
• Agent workflows that can load SKILL.md and reference documents

The repository uses a simple structure so it can be adapted to different platforms with minimal changes.

Installation

npm

Install the package from npm:

npm install user-centered-design-skill

The package contains the skill instructions and reference material:

• SKILL.md
• references/ucd-frameworks.md

Copy those files into your assistant's skill, project instruction, or reusable context system.

Codex

Copy or clone this folder into your Codex skills directory.

Example:

git clone https://github.com/wil0x/user-centered-design-skill.git ~/.codex/skills/user-centered-design

After installing, restart Codex or reload your skill environment so the new skill can be discovered.

Claude

For Claude, use this repository as a reusable skill or project-level instruction set:

1. Create a new skill, project, or custom instruction entry for user-centered-design.
2. Use the full contents of SKILL.md as the main instruction.
3. Add references/ucd-frameworks.md as supporting knowledge or attach it as a reference file.
4. Make sure Claude can access both files during the conversation.
5. Test the setup with a prompt such as:

Use the user-centered-design skill to evaluate this onboarding flow. Ask me for any missing context first.

Claude should respond by gathering product, user, task, pain point, mental model, and constraint information before giving recommendations.

Other AI Assistants

For assistants that do not have native skill support, use this skill as a structured instruction package:

1. Copy the contents of SKILL.md into the assistant's system prompt, custom instructions, project instructions, or reusable prompt library.
2. Keep references/ucd-frameworks.md available as a linked document, uploaded file, or additional context.
3. Tell the assistant to consult the reference file when it needs details about UCD frameworks, research methods, heuristics, or UX laws.
4. Preserve the trigger behavior from the description field in SKILL.md, so the assistant knows when to apply the skill.

Recommended adapter instruction:

When the user asks for UX, UCD, usability, interface analysis, personas, user journeys, onboarding, heuristic evaluation, or usability testing, apply the user-centered-design skill from SKILL.md. If more detail is needed, consult references/ucd-frameworks.md.

Files To Keep Together

This skill works best when these files stay together:

• SKILL.md: main behavior, trigger description, diagnostic workflow, output formats, and rules.
• references/ucd-frameworks.md: supporting UCD theory, examples, frameworks, laws, methods, and templates.

If your platform only accepts one text field, paste SKILL.md first, then add a note that the reference material from references/ucd-frameworks.md should be used as supporting context.

Skill Metadata

The skill is defined in SKILL.md with the following name:

name: user-centered-design

It is triggered when a request involves UCD, UX diagnosis, usability, design principles, personas, user journeys, heuristic evaluation, usability studies, onboarding, prototypes, or cognitive constraints.

Recommended Output Style

The skill encourages the assistant to answer with a practical structure:

## Diagnosis
[4 Pillars classification + current situation]

## Applied Principle
[Design principle being used and why]

## Main Recommendation
[One clear design decision]

## Action Plan
1. [Immediate quick win]
2. [Medium-term action]
3. [Structural change]

## How to Validate
- [Recommended test method]
- [Metric to track]

This keeps recommendations specific, testable, and connected to real user behavior.

Design Philosophy

This skill follows a few core principles:

• The user is never the problem; confusing behavior usually points to a design problem.
• Design is not decoration. It is a way to reduce friction and help people complete meaningful tasks.
• Good recommendations require context.
• Every design is a hypothesis until tested.
• A smaller, high-impact recommendation is better than a long generic checklist.

Contributing

Contributions are welcome. Useful improvements include:

• Additional UCD frameworks
• Better examples and prompt patterns
• More research templates
• Case-study-based recommendations
• Localization to other languages
• Practical checklists for specific product types

Please keep the skill operational: new content should help the assistant make better design decisions, not only explain concepts.

License

This project is licensed under the MIT License. See LICENSE for details.