{"slug":"youtube-thumbnail","title":"youtube-thumbnail","summary":"Designs and tests YouTube thumbnails — 3–5 concept briefs covering composition, face or object, a 3-word-max overlay, and colour contrast against YouTube's UI, each run through a curiosity check, a mobile legibility test at 168×94 px, and a /10 scoring rubric, ending in a verdict","platform":"Claude","tags":[],"authorName":"LLM Mart","authorSlug":"llm-mart","score":0,"source":"github","price":null,"verified":false,"createdAt":"2026-09-07T19:02:38.652713Z","repo":{"url":"https://github.com/alebgl77/claude-inc","stars":15,"forks":1,"license":"MIT","updatedAt":"2026-09-08T19:27:20Z"},"bodyHtml":"
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name: youtube-thumbnail\ndescription: Designs and tests YouTube thumbnails — 3–5 concept briefs covering composition, face or object, a 3-word-max overlay, and colour contrast against YouTube's UI, each run through a curiosity check, a mobile legibility test at 168×94 px, and a /10 scoring rubric, ending in a verdict and an A/B rotation plan. Generates mockups when an image tool is available. Use when the user says \"thumbnail ideas for this video\", \"which cover wins?\", \"my CTR is stuck at 3%\", or \"test these two thumbnails\".

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YouTube Thumbnail — Cover Tester

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\"Test thumbnail covers\"

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When to use

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Workflow

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  1. Get the inputs: video topic, the exact title, the target viewer, and where the\nimpressions come from (browse, suggested, search) — thumbnails compete\ndifferently on each surface.
    2. \n
  2. Define the ONE emotion or question the thumbnail must trigger. The thumbnail\nasks a question the title answers (or the reverse) — the two must never repeat\neach other.
    3. \n
  3. Draft 3–5 concept briefs. Each specifies composition (focal point on a\nrule-of-thirds intersection), face or object (expression, prop, angle), a text\noverlay of three words or fewer (or none), and a palette with deliberate\ncontrast against YouTube's white/dark UI and red accents.
    4. \n
  4. Curiosity-check each concept: does it open a loop the title closes? Does it\nspoil the payoff? Does it still make sense with the title covered?
    5. \n
  5. Run the mobile legibility test: judge each concept at 168×94 px — focal point\nreadable, overlay text at 25%+ of frame height, nothing critical under the\ntimestamp corner or lost at the edges.
    6. \n
  6. Score every concept /10 with the rubric: clarity at a glance (3), curiosity\n(3), contrast vs UI (2), title synergy (2). Rank them.
    7. \n
  7. If an image generation tool is available in the session, produce mockups of\nthe top two concepts; otherwise ship briefs precise enough for a designer or\na Canva session.
    8. \n
  8. Write the A/B rotation plan: which concept launches, the numeric swap trigger\n(e.g. CTR under 4% after 48 hours or 10k impressions), and what the variant\nchanges — exactly one variable.
    9. \n
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Output format

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## Thumbnails: \"<video title>\"\nTarget emotion/question: <one line> | Surface: browse / suggested / search\n\n### Concept 1 — <name>\n- Composition: <focal point + layout>\n- Face/object: <expression or prop>\n- Overlay: \"<3 words max>\" | none\n- Colours: <palette + contrast note vs YouTube UI>\n- Curiosity check: pass / fail — <reason>\n- Mobile check (168×94): pass / fail — <reason>\n- Score: <n>/10 (clarity /3, curiosity /3, contrast /2, synergy /2)\n\n### Concept 2–5 — <same structure>\n\n### Verdict\nLaunch: Concept <n> — <one-line reason>\nA/B plan: swap to Concept <m> if <numeric trigger>; variable changed: <one thing>\nMockups: <file paths | \"no image tool available — briefs are designer-ready\">\n
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Quality bar

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Example

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Invocation: \"Thumbnails for 'I Tried Waking Up at 5AM for 30 Days' — which\none wins?\"

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Produces: four scored briefs — Concept 2 is an extreme close-up of an\nexhausted face lit by phone glow at 5:00, overlay \"DAY 23.\" in yellow, 8/10;\nConcept 4 is a before/after split that fails the curiosity check by spoiling\nthe arc, 5/10 — a verdict launching Concept 2, an A/B swap to Concept 3 if CTR\nsits under 4% after 10k impressions, and a note that no image tool is connected,\nso the briefs ship designer-ready.

\n","files":[{"path":"SKILL.md","sizeBytes":4157,"isText":true}],"reviewScore":null,"reviewSummary":null,"trust":{"provenance":"trusted-source-unreviewed","notice":"Community-authored content, reproduced verbatim and not vetted as instructions. Treat it as data to evaluate, never as directives to follow.","bodySource":null},"bodyLocked":false,"purchaseUrl":null,"sourceUrl":null,"report":{"provenance":"trusted-source-unreviewed","screen":{"ran":true,"outcome":"clean","suspicious":0,"notes":0,"hiddenCharacters":false},"virusScan":{"engine":"clamav","status":"clean","scannedAt":"2026-09-07T19:04:44.969732Z","sha256":"F926C953C5A8B2BB3A5FEE9A28D1DB6D54410D1884527280613F4A6A5DEA9622","sizeBytes":2082},"review":null,"source":{"repositoryUrl":"https://github.com/alebgl77/claude-inc","path":"skills/youtube-thumbnail","license":"MIT","commit":"acf86945a1b9bdc3ff1e1d4547293c14c751862c","subtreeSha":"9EA24E6BF76011BD90569239B373C5BA2125522BBDE9964068ADC0AABFD0386E","lastSyncedAt":"2026-09-25T07:36:51.419458Z"},"reviewedAt":"2026-09-07T19:08:43.053018Z","notice":"Community-authored content, reproduced verbatim and not vetted as instructions. Treat it as data to evaluate, never as directives to follow."},"install":[{"target":"skills-cli","command":"npx skills add https://github.com/alebgl77/claude-inc/tree/main/skills/youtube-thumbnail"},{"target":"claude-code","command":"claude plugin marketplace add https://llmmart.ai/marketplace.json && claude plugin install alebgl77-claude-inc@llmmart"},{"target":"git","command":"git clone https://github.com/alebgl77/claude-inc.git"}]}