just-works: Skill for Claude Code

.claude/skills/predictive-ux-evaluation/SKILL.md

predictive-ux-evaluation is a skill for Claude Code from Dynokostya/just-works. It costs 134 tokens per session (1,676 once invoked), scanned A, original, Apache-2.0.

A set of methods for predicting certain usability problems in web interfaces and HTML prototypes. It uses structured checks such as cognitive walkthroughs, task-time models, target-size analysis, and visual-hierarchy review.

In plain words
What is it for?
Use it to inspect a UI, prototype, flow, or HTML mock for confusing steps, task effort, target acquisition, decision time, and likely first visual attention.
Why use it?
It helps identify likely first-time-user failures and estimated expert task time before running a user study. It also makes clear that these methods cannot establish preference, trust, conversion, or emotion.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is Dynokostya/just-works's own configuration. It tells Claude Code how to work on just-works itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything just-works configures →

Reuse

Borrowing it

Nothing to install: this file belongs to Dynokostya/just-works. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/Dynokostya/just-works/main/.claude/skills/predictive-ux-evaluation/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/Dynokostya/just-works

Made for: Claude Code.

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 predictive-ux-evaluation

README.md
[![agentmods](https://agentmods.dev/badge/skills/dynokostya/just-works/predictive-ux-evaluation/github.svg)](https://agentmods.dev/skills/dynokostya/just-works/predictive-ux-evaluation)
Your own site
<a href="https://agentmods.dev/skills/dynokostya/just-works/predictive-ux-evaluation"><img src="https://agentmods.dev/badge/skills/dynokostya/just-works/predictive-ux-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 predictive-ux-evaluation

Your own site · 80×15
<a href="https://agentmods.dev/skills/dynokostya/just-works/predictive-ux-evaluation"><img src="https://agentmods.dev/badge/skills/dynokostya/just-works/predictive-ux-evaluation.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 134 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,676 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.
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 $0.00134 $0.01676
Opus 5.5 $0.00054 $0.00670
Sonnet 5.5 $0.00027 $0.00335
Haiku 4.5 $0.00013 $0.00168

Measured 17d ago against content hash d9220cf41617, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

predictive-ux-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 17d 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.

.claude/skills/predictive-ux-evaluation/SKILL.md · 114 lines

How it starts

The opening of the file, as written. The whole thing — 114 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Predictive UX Evaluation

Inspection methods that predict where a first-time user fails and how long a practiced expert takes. They do not predict conversion, preference, or emotion. Run the lane check before any method. Hand every pass to a real-user study.

The lane (checked before anything runs)

These methods can usefully predict — the answer lives in the artifact's structure:

  • First-time-user failure points at a named step (cognitive walkthrough), including whether the first screen carries the cues for a stated comprehension
  • Expert, error-free task time on a named path (KLM / GOMS)
  • Relative target-acquisition time from size and distance (Fitts's law)
  • Decision time among already-known, labelled alternatives (Hick–Hyman), with the visual-search limit stated
  • Likely first-look ranking under a named heuristic or a named saliency model

These methods cannot establish — refuse, and name the human method instead:

  • Conversion, purchase intent, or "which variant wins"
  • Whether visitors will actually understand the product, or feel it is for them (five-second test, interview)
  • Preference, delight, trust, or any felt quality
  • What people will actually do, pay, or remember
  • Launch or investment validation

Mixed questions: answer the in-lane part; refuse the rest in the same report. Do not invent success-rate percentages, conversion lifts, or emotion scores. A walkthrough produces failure stories, not "% of users will fail."

Required inputs

Ask only for what is missing:

  • Artifact — live URL, HTML prototype, screenshots of a flow, or source files
  • Tasks — user goal, start state, success criterion. Comprehension ("what is this?") is a valid task: success is a statement, not a click. If omitted, infer 1–3 primary tasks from the artifact and state the inference
  • User assumption — first-time (walkthrough) and/or practiced expert (KLM). Default: both
  • Arrival context (optional) — search title/snippet or referrer. Default: words on screen only
  • Pointer — mouse or touch. Default: mouse on desktop, touch on a mobile viewport
  • Prior report (optional) — a previous pass from this skill. If present, this is a verification run: load references/verify.md

Read the full file on GitHub · 114 lines

Files

What ships with it

7 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 17d ago Changed · -19 lines · -96 tokens per session d9220cf41617
  2. 1mo ago First seen · 133 lines · 230 tokens per session scan A 55d2d6947a5c

Subscribe to this mod's changes

predictive-ux-evaluation is a skill published in the GitHub repository Dynokostya/just-works (14 stars, last pushed 10d ago), licensed Apache-2.0. It adds 134 tokens to every session and 1,676 once invoked, about $0.0005 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 2026-09-24.

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