Usability Testing Skill for Claude

Usability Testing

Plan and run tests that find usability problems before users hit them in production. Stack-agnostic. Tool-agnostic.

This skill is for testing existing designs or prototypes. For broader discovery research, use ux-research. For conversion testing in production, use cro-optimization.

When to use

• Before launching a new flow or major redesign
• After a redesign to verify it doesn't introduce new problems
• When analytics show drop-off but you don't know why
• When customer support tickets pattern around specific UI areas
• Pre-launch user validation
• Comparing two design directions

When NOT to use

• Discovery / generative research (use ux-research)
• Live conversion optimization (use cro-optimization)
• Mapping the broader experience (use journey-mapping)
• Pure quantitative measurement (use analytics-strategy)

Required inputs

• The design or prototype to test (functional or near-functional)
• Specific tasks users would do
• The audience (who should be tested)
• Testing infrastructure (moderated tool, unmoderated tool, in-person setup)

The framework: 5 phases

1. Define what to test

Don't test the whole product. Test specific tasks.

Task selection criteria:

• The task represents a real user goal (not "click around and explore")
• The task has a clear start and end
• The task is achievable in 2 to 10 minutes
• The task is one of: most common, most strategic, most problematic

Examples of testable tasks:

> "You want to find a contractor near you who can install a fence. Show me how you'd do that on this site."

> "You're a first-time visitor. You want to understand if this product fits your needs. Walk me through how you'd evaluate it."

> "Your team needs a new tool to manage projects. Use this site to figure out which plan is right for a 12-person team."

Task framing rules:

• State the user goal, not the system action ("find a place to stay" not "click the search button")
• Provide context (why are you doing this?)
• Don't reveal the path
• Don't use product terminology in the task framing

2. Choose moderated or unmoderated

Moderated (live, with researcher):

• Researcher observes and probes in real time
• Best for early-stage prototypes, complex tasks, novel concepts
• Higher cost, smaller sample (5 to 8 participants typical)
• Catches surprises and probe deeper

Unmoderated (recorded, asynchronous):

• Participant completes alone, often via tool (UserTesting, Maze, Lookback)
• Best for stable designs, simple tasks, larger sample
• Lower cost, larger sample (15 to 30 participants typical)
• Catches patterns at scale, less depth per session

For most teams: moderated for early/critical decisions, unmoderated for ongoing validation.

3. Recruit

Target audience - not just convenience.

Recruit criteria:

• Match real users (target audience, not just "anyone")
• Mix of experience levels with the product (new and existing if applicable)
• Mix of relevant device types (mobile, desktop, tablet if relevant)
• Exclude friends, family, employees

Sample size:

• Moderated: 5 to 8 participants (Nielsen's "5 users find 85% of usability issues" for the most common segment)
• Unmoderated: 15 to 30 participants (more participants compensate for less probing)
• Multi-segment testing: 5 to 8 per segment

4. Run the test

Pre-task setup:

• Confirm recording works
• Brief participant (purpose, anonymity, recording, "no wrong answers")
• Get verbal consent
• Have participant share screen if remote

Moderated session structure:

• Warm-up (2 to 3 min). Easy questions to put participant at ease.
• Pre-test questions (3 to 5 min). Background context, current behavior with similar products.
• Task 1 (5 to 10 min). Describe task. Have participant attempt while thinking aloud.
• Post-task questions (1 to 2 min). What was easy/hard? Anything confusing?
• Repeat for tasks 2, 3, 4 (typically 3 to 5 tasks per 60-minute session).
• Overall debrief (5 to 10 min). General reactions, comparisons to alternatives, anything else.
• Close (2 min).

Moderation principles:

• Encourage think-aloud ("What's going through your mind?")
• Don't help unless they're truly stuck (and even then, only after a long pause)
• Don't lead ("Are you looking for the menu?" - bad)
• Note where they hesitate, scroll, or backtrack
• Note their language vs the product's language
• Note emotional reactions

Anti-patterns:

• Talking too much (researcher should talk maybe 20% of the time)
• Defending the design when participants struggle
• Helping prematurely
• Asking participants to predict their future behavior
• Treating participant suggestions as features ("Users want X" - test demand for X separately)

5. Synthesize and report

Patterns across participants are signal. Single-participant complaints are weaker (but worth investigating).

Synthesis steps:

• Issue inventory. Every issue observed, with which participant, which task, severity.
• Cluster. Issues that are the same root problem.
• Severity.
• Critical: Blocks task completion. Most users hit this.
• Major: Significantly slows task. Many users hit this.
• Minor: Friction. Some users hit this. Workaround exists.
• Cosmetic: Polish. Doesn't affect task.
• Recommendations. For each issue, propose specific fixes.
• Prioritize. By severity and effort.

Report structure:

# Usability Test: [Design / flow]

## Summary
[2 to 3 paragraphs covering: what was tested, headline findings, top 3 priorities]

## Method
[Moderated/unmoderated, sample size, audience, dates, tasks]

## Critical findings
[Each with description, frequency, supporting evidence (quotes/clips), recommendation]

## Major findings
[Same structure]

## Minor findings
[Brief]

## Cosmetic findings
[Briefest]

## What worked well
[Calibration: capture successes too]

## Recommendations
[Prioritized list with effort estimates]

## Next steps
[Test re-run schedule, design iteration plan]

Workflow

• Define the goals. What decisions hinge on this? What tasks matter most?
• Design tasks. 3 to 5 specific, realistic, goal-framed tasks.
• Choose moderated vs unmoderated. Match to stage and depth needed.
• Recruit. Specific to audience.
• Pilot. 1 to 2 sessions before main batch. Refine tasks if needed.
• Run. Follow the protocol. Stay disciplined.
• Synthesize during, not just after. Patterns emerge by session 4 or 5.
• Report. Multiple formats - written report + highlight clips.
• Track fixes. Every critical issue should have an owner and date.

10. Re-test after fixes. Verify the fix worked, didn't introduce new issues.

Failure patterns

• Testing the whole product instead of specific tasks. Vague results.
• Tasks that reveal the path. ("Click the menu and find...")
• Friends and family as participants. Biased, not representative.
• Researcher leading the participant. Findings reflect the researcher.
• Defending the design when participants struggle. Misses real issues.
• Helping too quickly. Participant doesn't experience the friction.
• Treating participant suggestions as features. Users solve their problem; product team designs the solution.
• One participant = data point. A single strong opinion isn't a finding.
• Skipping severity scoring. All findings treated equally; team can't prioritize.
• Reports no one reads. Highlight clips and live walkthroughs work better than 80-page decks.
• Testing once, never re-testing. Fixes that introduce new problems go undetected.

Output format

Default outputs:

• Test plan (before testing) - usability-test-plan-[topic].md
• Task script (per session) - usability-tasks-[topic].md
• Findings report (after synthesis) - usability-findings-[topic].md
• Highlight clips (separately produced)

Reference files

• references/task-script-patterns.md - Task framing patterns by common product type, with good and bad examples.