youtube-thumbnail

What the source does

• FilesystemNone observedNo reads or writes in the source
• NetworkNone observedNo outbound calls in the source
• ShellNone observedNo commands run in the source
• DependenciesPinnedNothing floats
• SecretsNone foundNo keys in source

Five audit layers

Gates applied: no behavioural pass.

Paste this into a new Gemini chat, attach your reference photo, enable Create Image, and select Nano Banana

Audit 0.4.1 · source sha 7179b9176eab · 31 Oct 2026Report an issue or request a re-scan

• Publishercharlie947 GitHub userOwner of the repository this skill is read from
• Source foldercharlie947/social-media-skills/skills/youtube-thumbnailThe exact folder we audited
• LicenceMITAs the repository states it
• Commit pinned for this verdict7179b9176eabA new audit runs when the source changes
• Repository statusNot archivedLast push 12 days ago
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: Generate a branded YouTube thumbnail from a video title. Uses a reference photo of the creator, high-CTR thumbnail principles, and brand colours to produce a ready-to-generate image prompt for Gemini. Use this skill…

---
name: youtube-thumbnail
description: >
  Generate a branded YouTube thumbnail from a video title. Uses a reference photo of the creator, high-CTR thumbnail principles, and brand colours to produce a ready-to-generate image prompt for Gemini. Use this skill whenever the user says "thumbnail", "youtube thumbnail", "build me a thumbnail", or wants a video cover image before writing the script. The thumbnail-first workflow mirrors the graphic-first approach for LinkedIn: sells the video before anyone hears a word of the script.
---

# YouTube Thumbnail

## Codex and Claude runtime

- Use this skill in Codex or Claude with the tools actually available in the current task. `AskUserQuestion` examples describe the questions, not a required API: use an available question tool within its limits, or ask in chat. Reuse answers and source material already supplied.
- Work in the user-selected project. Read its `about-me.md`, `voice.md` and relevant brand files before personalised work. Confirm the intended author if files conflict or contain starter defaults. Ask for missing facts or run `voice-builder`; never inherit the maintainer's identity, accounts or private files.
- Resolve bundled `references/` relative to this skill folder. For an explicitly requested profile refresh, read and update the canonical `about-me.md`, `voice.md` or `newsletter-voice.md` in place, preserving unrelated user facts and rules. Consumers must reread those canonical files. Use a new filename only for new deliverables that would collide with unrelated existing files. Installation alone never starts an interview or writes files. Do not write persistent learnings unless requested.
- Use supplied evidence first. Verify external claims through available search/source tools when needed. If a source or integration is unavailable, name the missing capability and offer supplied text/export input. Never invent facts, first-person experience, metrics or a successful tool run.
- Connect only services needed for the chosen route through the user's existing account. Never print credentials or overwrite connections. Drafting, saving and reviewing do not authorise publishing, sending messages or changing accounts.

## Visual completion state

This skill's image prompts are **prompt-ready**, not generated or visually reviewed assets. Keep its named Gemini workflow unless the user requests another generator. A missing image service does not block writing a prompt. When images are supplied or generated, open and inspect each export at full size and feed size (about 360px wide, 320px for thumbnails). Check exact copy, dimensions, clipping, legibility, brand colours, font appearance, logos and reference fidelity. Fix and re-inspect failed exports. Record any unavailable export or inspection as pending. An image prompt or raster export is not an editable design file.

## CRITICAL: Auto-start on load

When this skill triggers, go straight to Step 1.

## Step 1. Gather inputs

Check the project for a reference photo config. Look in this order:

1. `thumbnail-config.md` in the project root
2. `brand-kit.md` — look for a reference image path and brand colours
3. `about-me.md` — for the creator's name and positioning

If a reference photo path is stored, pre-fill it. Otherwise ask:

> Upload or provide the path to the reference photo of yourself you want used in the thumbnail. Ideally a clear headshot with distinctive lighting and expression you plan to reuse across videos for brand consistency.

Then call AskUserQuestion:

```json
[
  {
    "question": "What is the video title?",
    "header": "Title",
    "multiSelect": false,
    "options": [
      {"label": "I will type the title", "description": "Type the full working title"},
      {"label": "Suggest one", "description": "Given the topic, propose 3 click-worthy titles first"}
    ]
  },
  {
    "question": "Emotional tone?",
    "header": "Tone",
    "multiSelect": false,
    "options": [
      {"label": "Shock / surprise", "description": "Wide eyes, open mouth, bold reaction"},
      {"label": "Curious / thinking", "description": "Slight smirk, raised eyebrow, gaze off-frame"},
      {"label": "Confident / direct", "description": "Eye contact, calm, assertive"},
      {"label": "Frustrated / strong take", "description": "Intense gaze, hand gesture, tension"}
    ]
  }
]
```

Confirm the title and promise against the video’s supplied content. Do not invent a result, imply a demonstration exists, or use an unprovided face or brand mark. A missing reference photo leaves photo-based generation pending, while a composition brief can still be drafted.

## Step 2. Apply thumbnail best practices

Every thumbnail must follow these rules:

- **Face fills 30 to 50 percent** of the frame. Readable at small sizes.
- **3 to 5 words maximum** of large text. 6 if absolutely necessary.
- **Two colours dominate**. Brand primary + one high-contrast accent (yellow, red, cyan work well).
- **One clear focal element** besides the face. Tool logo, bold number, arrow, or prop.
- **High contrast** between face, text, and background. Test by squinting.
- **Text is not a sentence**. It is a hook phrase. Examples: "I fired my team", "Claude can now...", "Don't do this".
- **No small text, no logos bottom-right** (watch time icon sits there).

## Step 3. Build the thumbnail brief

Output a concise brief the user can review:

```
THUMBNAIL BRIEF: [video title]

Composition: [face position, % of frame, direction of gaze]
Text: "[hook phrase, 3-5 words]"
Text placement: [left, right, top, wraps around face]
Colour palette: [primary hex], [accent hex], [background hex]
Supporting element: [logo / prop / arrow / number]
Emotional tone: [tone from Step 1]
```

Then ask:

> Here's the brief. Say "generate" to output the image prompt or tell me what to change.

## Step 4. Output the Gemini prompt

Once approved, output the image generation prompt in a code block:

```
Using the attached reference photo of me, generate a Yo

Excerpt, first 6,000 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

1. 2026-10-31
   ✓SAFE B 89 / 100

   first audit · source 7179b9176eab

Questions about youtube-thumbnail

• github.com/charlie947/social-media-skills/tree/main/skills/youtu — the audited source at commit 7179b9176eab and every finding aboveObserved · 31 Oct 2026

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