Usability review with Krug's principles and Nielsen's ten heuristics, scored by severity.
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SKILL.md
UX Heuristics Framework
Practical usability principles for evaluating and improving user interfaces. Users don't read, they scan; they don't make optimal choices, they satisfice; they don't figure out how things work, they muddle through.
Core Principle
"Don't Make Me Think" — every page should be self-evident. If something requires thinking, it's a usability problem. Users have limited patience and cognitive bandwidth, so design for the scanning, satisficing, and muddling-through behavior described above.
Scoring
Goal: 10/10. Audit the interface, rate every issue on the severity scale below, then score the interface from its Quick Diagnostic results: start at 10 and subtract per failed diagnostic row, weighted by the worst severity it triggers (catastrophic/major rows cost ~2, minor/cosmetic ~1). Bands: 9-10 = no severity-3+ issues and ≤1 failed diagnostic row; 6-8 = some major issues or several failed rows; 3-5 = a catastrophic issue or many failed rows; ≤2 = core tasks blocked. Always state the current score, the highest-severity issues, and the specific fixes needed to reach 10/10.
Krug's Usability Principles
Laws 1-3 are Krug's Three Laws of Usability; #4, the Trunk Test, is his navigation orientation check.
Core concept: Every question mark that pops into a user's head adds cognitive load and distracts from the task.
Why it works: Users are on a mission — they don't want to puzzle over labels or decode clever marketing language. The less thinking required, the more likely they complete the task.
Key insights:
Clever names lose to clear names every time
Marketing-speak creates friction; plain language removes it
Unfamiliar categories force users to stop and interpret
Ambiguous links and buttons cause hesitation
Product applications:
Context
Application
Example
Navigation labels
Self-evident names
"Get directions" not "Calculate route to destination"
Avoid jargon: "Save" not "Persist", "Remove" not "Disassociate"
If a label needs explanation, simplify the label
Ethical boundary: Clarity should serve users — never use plain language as a veneer to hide unfavorable terms.
See: references/krug-principles.md when you need the full Krug method — scanning/satisficing/muddling psychology, the goodwill reservoir, homepage and tagline guidance, and the $0 usability-testing protocol (how many users, the test script).
2. It Doesn't Matter How Many Clicks
Core concept: The myth says "users leave after 3 clicks." In reality users don't mind clicks if each one is painless, obvious, and confidence-building.
Why it works: Cognitive effort per click matters more than click count. Users abandon when they lose confidence, not when they run out of patience for clicking.
Key insights:
Each click should be painless, obvious, and confidence-building
Three mindless clicks beat one click that requires deliberation
Shallow nav with clear labels beats deep nav with vague ones
Progress indicators: "Step 2 of 4: Shipping details"
Confirmations at each step: "Great, your email is verified. Now let's set up your profile."
Clear link text: "View all running shoes" not "Click here"
Ethical boundary: Never use extra steps to bury cancellation flows — every click should move users toward their goal, not away from it.
3. Get Rid of Half the Words
Core concept: Remove half the words on each page, then half of what's left. Brevity makes useful content prominent and respects the user's time.
Key insights:
Happy-talk ("Welcome to our website!") wastes space
Instructions nobody reads should be removed
"Please" and "Kindly" and polite fluff add noise
Shorter pages mean less scrolling and faster scanning
Product applications:
Context
Application
Example
Landing pages
Cut welcome copy, lead with value
Remove "Welcome to..." paragraphs
Error messages
State problem and fix, nothing more
"Password too short (min 8 chars)"
Empty states
Action-oriented, minimal
"No results. Try a different search."
Copy patterns:
Before: "Please kindly note that you will need to enter your password in order to proceed to the next step." → After: "Enter your password to continue."
Before: "We've received your message and will get back to you as soon as possible." → After: "Message sent. We'll reply within 24 hours."
Ethical boundary: Brevity must not omit critical information — concise disclosures for pricing, terms, and data usage are a user right.
4. The Trunk Test
Core concept: Drop a user on any random page (like being released from a car trunk at a random spot) — they should instantly answer six orientation questions: What site is this? What page? What are the major sections? What are my options here? Where am I in the hierarchy? Where's search?
Why it works: Good navigation gives constant orientation. Users who can't tell where they are feel lost and leave.
Apply it as the navigation check: page titles must match the link the user clicked, a "you are here" indicator (highlighted nav item, bold breadcrumb) must be present, and section headings must orient ("Your Account > Billing" not just "Settings").
Ethical boundary: Navigation labels must honestly represent site structure — never use misleading labels to funnel users into marketing pages.
See: references/krug-principles.md when running the Trunk Test or designing navigation — it maps each of the six questions to the page element that answers it, plus breadcrumb and permanent-navigation rules.
Nielsen's 10 Usability Heuristics
1. Visibility of System Status
Keep users informed through timely feedback. Every action needs acknowledgment — progress bars for uploads, confirmations for submissions, skeleton screens for loading. Silent failures destroy trust. Copy pattern: "Saving..." → "Saved".
2. Match Between System and Real World
Speak users' language: "Sign in" not "Authenticate", "Search" not "Query." Follow real-world metaphors (trash bin, shopping cart) and natural ordering (street → city → state → zip).
3. User Control and Freedom
Provide clear "emergency exits." Undo beats "Are you sure?" dialogs — users click through confirmations without reading. Every flow needs cancel/exit, and back buttons must never break.
4. Consistency and Standards
Same words, styles, and behaviors mean the same thing throughout. Internal consistency (your app) plus external consistency (platform conventions: logo top-left, search top-right). One term per concept — "Projects" everywhere, never mixed with "Workspaces."
5. Error Prevention
Prevent problems before they occur: constrained inputs (date pickers over text fields), autocomplete, sensible defaults, "unsaved changes" warnings. Slips (accidental wrong action) and mistakes (wrong intention) need different prevention.
6. Recognition Rather Than Recall
Minimize memory load — show options, don't require memorization. Breadcrumbs, recent searches, pre-filled fields, dropdowns with decoded values. Working memory holds ~7 items; recognition is far easier than recall.
7. Flexibility and Efficiency of Use
Serve both novices and experts: keyboard shortcuts, bulk actions, saved searches, command palettes (Cmd+K). Progressive disclosure keeps it simple for beginners while experts access full power.
8. Aesthetic and Minimalist Design
Every element must earn its place — when everything screams for attention, nothing stands out. Show what matters now, hide what doesn't. One primary CTA per page.
9. Help Users Recognize, Diagnose, and Recover from Errors
Error messages need three parts: what happened, why, and how to fix it. Plain language ("Connection failed" not "ECONNREFUSED"), specific ("Password must be 8+ characters" not "Invalid"), never blame the user, preserve their input.
10. Help and Documentation
Help should be searchable, task-focused ("How to..." not technical reference), and contextual (tooltips, inline hints, guided tours).
See: references/nielsen-heuristics.md when auditing against a specific heuristic — it expands each of the 10 into good-implementation / common-violation / severity tables with copy patterns and ethical boundaries.
Severity Rating Scale
Rate each issue found in an audit:
Severity
Rating
Description
Priority
0
Not a problem
Disagreement, not usability issue
Ignore
1
Cosmetic
Minor annoyance, low impact
Fix if time
2
Minor
Causes delay or frustration
Schedule fix
3
Major
Significant task failure
Fix soon
4
Catastrophic
Prevents task completion
Fix immediately
Weigh three factors: frequency (how often it occurs), impact (how severe when it occurs), persistence (one-time or ongoing).
See: references/audit-template.md when running a full heuristic evaluation — a structured per-screen template that captures issues, severity, and recommended fixes in a consistent format.
Common Mistakes
Mistake
Why It Fails
Fix
Mystery meat navigation
Icons without labels force guessing
Add text labels alongside icons
Too many choices
Decision paralysis slows users
Reduce to 7 plus/minus 2 items
No "you are here" indicator
Users feel lost in the hierarchy
Highlight current section in nav and breadcrumbs
No inline validation
Submit, error, scroll cycle frustrates
Validate on blur with specific messages
Unclear required fields
Users confused about what's mandatory
Mark optional fields, not required
Wall of text
Nobody reads dense paragraphs
Break up with headings, bullets, whitespace
Jargon in labels
Users don't speak your internal language
User-test all labels, use plain language
No loading indicators
Users think the system is broken
Show spinner, progress bar, or skeleton screen
Tiny tap targets
Mobile users misclick constantly
Minimum 44x44 px touch targets
Hover-only information
Mobile and keyboard users miss it
Don't hide critical info behind hover
No undo
Users afraid to take any action
Provide undo for all non-destructive actions
Poor error messages
"Invalid input" tells users nothing
Explain what's wrong and how to fix it
Low contrast text
Unreadable for many users
WCAG AA minimum (4.5:1 contrast)
Inconsistent nav location
Users can't find navigation
Fixed position, same place on every page
Broken back button
Violates the browser contract
Never hijack or break browser history
See: references/wcag-checklist.md when auditing accessibility (contrast, keyboard, screen-reader, focus) — a complete WCAG 2.1 AA checklist with testing tools. See references/cultural-ux.md when designing for global audiences — RTL layouts, color meanings, form/name/date conventions, and localization pitfalls.
Quick Diagnostic
Question
If No
Action
Can I tell what site/page this is immediately?
Users are lost
Add clear logo, page title, breadcrumbs
Is the main action obvious?
Users don't know what to do
Visual hierarchy, single primary CTA
Is the navigation clear?
Users can't find their way
Apply the Trunk Test, add "you are here" indicators
Can I find the search?
Goal-driven users are blocked
Visible search box in header
Does the system show what's happening?
Users lose trust and re-click
Loading states, confirmations, progress
Are error messages helpful?
Users get stuck
Plain language with a specific fix
Can users undo or go back?
Users are afraid to act
Undo, cancel, and back options everywhere
Does it work without hover?
Mobile/keyboard users excluded
Visible alternatives to hover interactions
Are all interactive elements labeled?
Users guess at icons
Text labels or descriptive tooltips
Does anything make me stop and think "huh?"
Cognitive load too high
Simplify — if it needs explanation, redesign it
Heuristic Conflicts
Heuristics sometimes contradict each other. When they do:
Simplicity vs. Flexibility: use progressive disclosure
Consistency vs. Context: consistent patterns, contextual prominence
Efficiency vs. Error Prevention: prefer undo over confirmation dialogs
Discoverability vs. Minimalism: primary actions visible, secondary hidden
See: references/heuristic-conflicts.md when two heuristics pull in opposite directions and the four rules above don't settle it — resolution frameworks with worked trade-off examples.
Dark Patterns Recognition
Dark patterns violate heuristics deliberately to manipulate users: forced continuity (hard to cancel), roach motel (easy in, hard out), confirmshaming (guilt-based options), hidden costs (surprise fees at checkout).
See: references/dark-patterns.md when you suspect a design manipulates rather than serves users — the complete taxonomy, ethical alternatives, and relevant regulations.
When to Use Each Method
Method
When
Time
Findings
Heuristic evaluation
Before user testing
1-2 hours
Major violations
User testing
After heuristic fixes
2-4 hours
Real behavior
A/B testing
When optimizing
Days-weeks
Statistical validation
Analytics review
Ongoing
30 min
Patterns and problems
Further Reading
Based on usability principles developed by Steve Krug and Jakob Nielsen:
Steve Krug is a usability consultant whose Don't Make Me Think (2000, revised 2014) is the most widely read book on web usability. He demonstrated that usability testing doesn't require a lab or large budget — just watching a few real users try to accomplish tasks.
Jakob Nielsen, PhD is co-founder of the Nielsen Norman Group and author of the 10 Usability Heuristics (1994), still the most-used framework for heuristic evaluation worldwide. The New York Times called him "the guru of Web page usability."
