# Thumbnail Ab Tester

> Generates multiple thumbnail concepts for the same clip and ranks them by hook strength using contrast, face presence, text legibility, and emotional cue heuristics. Trigger when user wants thumbnail options, A/B test thumbnails, or improve CTR on Reels/Shorts/YT.

- Skill: `rahulcommercial/thumbnail-ab-tester` (Agent Skill)
- Install (CLI): `npx skillmds@latest add rahulcommercial/thumbnail-ab-tester`
- Raw SKILL.md: https://api.skillmd.com/api/skills/rahulcommercial/thumbnail-ab-tester/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: rahulcommercial (https://skillmd.com/u/rahulcommercial)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/rahulcommercial/thumbnail-ab-tester

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# Thumbnail A/B Tester

Generate 3-5 thumbnail concepts, score them, ship the winner.

## When to use

- User has a video and wants 3+ thumbnail variants.
- User wants critique on an existing thumbnail.
- User wants to know which still frame from a clip is strongest.

## Variant generation strategy

For one clip, produce variants across these axes:

| Axis | Option A | Option B | Option C |
|---|---|---|---|
| **Frame** | Hook moment (start) | Climax (mid) | Payoff (end) |
| **Text** | One word | Short phrase | None (visual only) |
| **Face** | Tight crop (eyes visible) | Medium shot | Object only |
| **Contrast** | Dark bg + bright subject | Inverted | High saturation |

Pick one option per axis → 3-5 thumbnails total. Don't generate 30 — too much noise.

## Scoring rubric (0-10 each, sum / 40)

| Factor | What to check |
|---|---|
| **Hook clarity** | Can a viewer read the *story* in < 1 sec? |
| **Face / emotion** | If a face: is the emotion strong & specific? |
| **Text legibility** | Readable at 320px wide (IG feed size)? |
| **Contrast** | Subject pops from background? |

## Heuristics (the boring stuff that matters)

- Faces with **visible eyes** outperform face-from-behind ~2:1 on IG.
- Bright single-colour backgrounds (yellow, red) beat busy stills.
- Text on thumbnail: ≤ 4 words. Beyond that, no one reads.
- Avoid feed-camouflage: if your thumbnail looks like 5 others on the explore grid, it loses.

## When to NOT use a thumbnail

- IG Reels cover image is shown on grid only, not feed. Optimise for **grid coherence** + **first-frame hook in the video**, not feed clicks.
- YT Shorts: thumbnail = first frame by default. Either accept it or pin a custom cover.

## Output

```
Variant A — score 32/40
  Frame: t=2.4s (climax)
  Text: "₹4,300 in 14 min"
  Notes: high contrast, specific number, face in lower third
  Strongest factor: hook clarity

Variant B — score 28/40
  ...

Winner: A
Why: specific number + face emotion drives the highest CTR pattern.
```

## What NOT to do

- Don't fabricate emotions / numbers in thumbnails. Clickbait that doesn't deliver tanks your reach next post.
- Don't use ©'d game promotional art as a thumbnail.