YouTube Thumbnail
Design a high-CTR YouTube thumbnail — striking imagery, bold text placement, and emotional face/subject if needed.
Inputs
| Name | Type | Required | Default | Description |
|---|---|---|---|---|
title | text | yes | — | The video title or topic (e.g. "I tried 7 AI tools in 24 hours — here's what happened"). |
channel_style | text | no | bold, high contrast, bright colors, clean design, YouTube tech aesthetic | Channel brand style (e.g. "dark moody gaming", "bright educational", "minimal corporate"). |
subject_description | text | no | — | Optional description of the person or subject to feature (e.g. "a surprised young man in a hoodie"). |
Steps
Thumbnails are the #1 factor in YouTube CTR. Generate a single, maximum-impact 16:9 image.
Phase A — Plan the composition
Before generating, briefly reason about the best thumbnail formula for this topic:
- Emotion-first: shocked/curious face if relevant + bold text = high CTR
- Text overlay: 3–5 words max, high-contrast (white/yellow on dark, or vice-versa)
- Contrast & saturation: thumbnails compete in a grid — they must pop
Phase B — Generate the thumbnail
- Build the image generation prompt:
- Subject:
{{subject_description}}if provided, otherwise design an object/scene that dramatizes the topic. - Mood: derives from
{{channel_style}}. - Composition: rule-of-thirds, subject on left or right with empty space for text.
- Style tags:
{{channel_style}}, youtube thumbnail composition, ultra detailed, vibrant, high contrast, 16:9.
- Call
muapi image generate(model=gpt-image-2-text-to-image, aspect_ratio=16:9).
Phase C — Text overlay guidance
After generation, return:
- Suggested overlay text: 3–5 bold words that complement the title
{{title}}. - Text placement: where on the canvas to position text (e.g. "bold yellow text, top-right third").
- Font recommendation: style suggestion (e.g. "Impact-style all-caps with black outline").
Notes
- Never put too much text in the prompt — text rendering in image models is unreliable. Guide the user on adding text in post-production (Canva, Photoshop).
- If the user already has a channel image or face photo in the session, use
muapi image editto incorporate it. - Suggest A/B variants only if the user asks.
Trigger Keywords
youtube thumbnail, yt thumbnail, thumbnail, video thumbnail, youtube cover
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Notes for the Executing Agent
- This recipe is LLM-orchestrated: read each phase, gather any missing inputs from the user, then call
muapiCLI commands. Usemuapi auth configurefirst ifMUAPI_API_KEYis unset. - For model IDs without a CLI alias yet, fall back to the raw endpoint via
curl -X POST https://api.muapi.ai/api/v1/<endpoint> -H "x-api-key: $MUAPI_API_KEY" -H 'content-type: application/json' -d '{...}'and poll withmuapi predict wait <request_id>. - Substitute
{{input_name}}placeholders with the user's actual inputs before issuing each call.
