Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/slogsdon/skills-designnpx agentmods add skills/slogsdon/skills-design/design-youtube-thumbnailWrote 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.
[](https://agentmods.dev/skills/slogsdon/skills-design/design-youtube-thumbnail)<a href="https://agentmods.dev/skills/slogsdon/skills-design/design-youtube-thumbnail"><img src="https://agentmods.dev/badge/skills/slogsdon/skills-design/design-youtube-thumbnail/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.
<a href="https://agentmods.dev/skills/slogsdon/skills-design/design-youtube-thumbnail"><img src="https://agentmods.dev/badge/skills/slogsdon/skills-design/design-youtube-thumbnail.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00080 | $0.02832 |
| Opus 5 | $0.00040 | $0.01416 |
| Sonnet 5 | $0.00016 | $0.00566 |
| Haiku 4.5 | $0.00008 | $0.00283 |
Grade A, and why
design-youtube-thumbnail 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 12d 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.
How it starts
The opening of the file, as written. The whole thing — 231 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Skill: youtube-thumbnail
Produces a pixel-exact 1280×720 HTML canvas. The defining constraint: it must read clearly at 240×135px (typical mobile feed thumbnail) — not just at full size. Bias toward fewer words, larger type, higher contrast than other platform skills.
When to use
- User has (or is about to publish) a YouTube video and wants a thumbnail asset
- A
DESIGN.mdexists for the brand
Inputs
- Required: brand slug, video title (the ACTUAL video title, not the on-thumbnail text)
- Required: thumbnail text — the 2–4 words that go ON the image (this is NOT the video title; it's the visual hook)
- Optional: episode/series number, supporting micro-text (max 6 words)
Output
./design/<brand-slug>/artifacts/youtube-YYYY-MM-DD-<slug>.html
Steps
1. Verify brand exists
test -f ./design/<brand-slug>/tokens.css
2. Gather the brief
Ask in one message:
1. Video title (full title that goes in YouTube's title field)
2. Thumbnail text — 2–4 words MAX that appear ON the image. This is your visual hook, not your title.
Examples: "Built it wrong" / "Faster than you'd think" / "Why I quit Vim" / "Day 47"
3. Optional episode/series marker (e.g. "EP. 12" or "PART 3 / 5")
4. Optional supporting micro-text under the hook (max 6 words)
If the user gives you 8+ words for thumbnail text, push back: "That's too many for legibility at mobile size. Pick the 3–4 words that carry the hook." Don't proceed until they agree.
3. Pick variation — ARCHITECTURE FIRST
Pick ONE archetype before any other axis. YouTube thumbnails have specific archetypes that work at small sizes; pick from these.
- Architecture archetype (pick FIRST):
text-only— the hook is the entire artifact. No marker, no mark, no rules. Default for maximum legibility.single-word— one massive word fills 70%+ of canvas; everything else absent.number-led— a number/stat dominates (e.g. "47", "0.3s", "$11M"); hook becomes caption.object-of-content— looks like a screenshot/quote from the video itself (transcript line, terminal output, code fragment).pattern-led— repetition or grid fills canvas; one element breaks it.chrome-led— marker + hook + corner mark. Last resort. Use only if the brand requires consistent chrome AND no other archetype suits.
What ships with it
1 file 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.
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.
- 12d ago First seen · 231 lines · 80 tokens per session scan A 4d5619c770dc
design-youtube-thumbnail is a skill published in the GitHub repository slogsdon/skills-design (3 stars, last pushed 28d ago), licensed MIT. It adds 80 tokens to every session and 2,832 once invoked, about $0.0004 per session on Opus 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 2026-08-31.
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