heuristic-evaluation

heuristic-evaluation is a skill for Claude Code from Owl-Listener/designer-skills. It costs 50 tokens per session (430 once invoked), scanned A, original, MIT.

An expert review method for finding usability problems in digital interfaces using Nielsen's ten usability guidelines. It documents each issue and rates its severity.

In plain words
What is it for?
Use it to inspect screens and task flows, identify violated usability guidelines, record where issues occur, and prioritize fixes.
Why use it?
It finds common interface problems before recruiting test participants, making early design review more structured.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the prototyping-testing plugin — 10 skills, 4 commands shipped together

Good fit Use it to inspect screens and task flows, identify violated usability guidelines, record where issues occur, and prioritize fixes.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/owl-listener/designer-skills/heuristic-evaluation
About the project

Owl-Listener/designer-skills is a collection of AI-agent skills, commands, and plugins for design work, covering research, design systems, interfaces, interaction, and delivery. Designers and developers use it inside coding assistants to guide design tasks, and the catalogue entries represent selected parts of that larger collection.

Owl-Listener/designer-skills · 3,079 stars · on GitHub

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add Owl-Listener/designer-skills --skill heuristic-evaluation
Clone the repo
git clone --depth 1 https://github.com/Owl-Listener/designer-skills

Made for: Claude Code.

Or install prototyping-testing, the plugin that ships this one along with the rest of its 10 skills, 4 commands.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for heuristic-evaluation

README.md
[![agentmods](https://agentmods.dev/badge/skills/owl-listener/designer-skills/heuristic-evaluation/github.svg)](https://agentmods.dev/skills/owl-listener/designer-skills/heuristic-evaluation)
Your own site
<a href="https://agentmods.dev/skills/owl-listener/designer-skills/heuristic-evaluation"><img src="https://agentmods.dev/badge/skills/owl-listener/designer-skills/heuristic-evaluation/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for heuristic-evaluation

Your own site · 80×15
<a href="https://agentmods.dev/skills/owl-listener/designer-skills/heuristic-evaluation"><img src="https://agentmods.dev/badge/skills/owl-listener/designer-skills/heuristic-evaluation.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 50 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 430 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket pass 15 Sept 2026
  • Snyk pass 15 Sept 2026
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00050 $0.00430
Opus 5.5 $0.00020 $0.00172
Sonnet 5.5 $0.00010 $0.00086
Haiku 4.5 $0.00005 $0.00043

Measured 1mo ago against content hash 6bdacce0f15d, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

heuristic-evaluation scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

prototyping-testing/skills/heuristic-evaluation/SKILL.md · 42 lines

What it actually says

Heuristic Evaluation

You are an expert in conducting systematic heuristic evaluations of digital interfaces.

What You Do

You evaluate interfaces against established usability heuristics to identify problems before user testing.

Nielsen's 10 Usability Heuristics

  1. Visibility of system status — Users know what is happening
  2. Match real world — System speaks users' language
  3. User control and freedom — Easy undo and exit
  4. Consistency and standards — Follow conventions
  5. Error prevention — Prevent problems before they occur
  6. Recognition over recall — Make options visible
  7. Flexibility and efficiency — Shortcuts for experts
  8. Aesthetic and minimalist design — No irrelevant information
  9. Error recovery — Help users recognize and recover from errors
  10. Help and documentation — Provide assistance when needed

Evaluation Process

  1. Define scope (which screens/flows to evaluate)
  2. Walk through as a new user
  3. Walk through as an experienced user
  4. Walk through each task flow
  5. Document each issue found
  6. Rate severity
  7. Compile and prioritize findings

Issue Documentation

For each issue: heuristic violated, description, location, severity (0-4), screenshot/reference, recommendation.

Severity Scale

  • 0: Not a usability problem
  • 1: Cosmetic only
  • 2: Minor problem
  • 3: Major problem (important to fix)
  • 4: Catastrophe (must fix before release)

Best Practices

  • Multiple evaluators find more issues (3-5 ideal)
  • Evaluate independently before comparing
  • Focus on real user tasks, not edge cases
  • Don't just find problems — suggest solutions
  • Combine with real user testing for complete picture
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 1mo ago First seen · 42 lines · 50 tokens per session scan A 6bdacce0f15d

Subscribe to this mod's changes

heuristic-evaluation is a skill published in the GitHub repository Owl-Listener/designer-skills (3,079 stars, last pushed 1mo ago), licensed MIT. It adds 50 tokens to every session and 430 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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