---
title: ToolRouter — Tool Detail
description: Detailed documentation for a ToolRouter tool including skills, parameters, and examples.
url: https://toolrouter.com/tools/youtube-thumbnails
---
# YouTube Thumbnails

Generate high-performing YouTube thumbnails optimized for clicks. Choose from proven thumbnail styles used by top creators — reaction faces, before/after, versus, tutorials, and more. Outputs at the exact 1280x720 spec YouTube requires with text rendering, bold compositions, and vibrant colors.

- **Version:** 0.01
- **Categories:** media, ai

## Skills (1)

### Generate Thumbnail (`generate_thumbnail`)

Generate YouTube thumbnails from a video topic. Supports 10 proven styles, text overlays, reference images for brand/face consistency, and batch generation for A/B testing.

**Parameters:**

| Name | Type | Required | Description |
|------|------|----------|-------------|
| `topic` | string | Yes | Video topic or thumbnail concept (e.g. "unboxing the new iPhone", "how I lost 50 pounds in 6 months") |
| `style` | string | No | Thumbnail style: reaction, before_after, versus, tutorial, listicle, product, storytime, travel, gaming, food (reaction, before_after, versus, tutorial, listicle, product, storytime, travel, gaming, food) |
| `text_overlay` | string | No | Bold text to render on the thumbnail (3-5 words max, e.g. "I QUIT MY JOB", "$10K IN 30 DAYS"). Rendered in thick sans-serif with contrasting outline. |
| `mood` | string | No | Emotional tone (e.g. "shocking", "inspiring", "mysterious", "exciting", "cozy", "dramatic") |
| `color_scheme` | string | No | Color guidance (e.g. "red and yellow", "dark with neon accents", "warm golden tones", "blue gradient") |
| `reference_images` | array | No | URLs of reference images — face photos for consistency, brand assets, or style references. First image is primary. |
| `additional_details` | string | No | Extra prompt details for fine-tuning the composition, subject, or scene (e.g. "person wearing red hoodie on left side", "luxury car in background") |
| `num_images` | number | No | Number of thumbnail variations to generate (1-12). Use 4-6 for A/B testing selection. Defaults to 1. [default: 1] |
| `model` | string | No | Image model to use. Defaults to Nano Banana 2 (best text rendering + quality). Use generate-image list_models for alternatives. |
| `seed` | number | No | Random seed for reproducible results. |
| `output_format` | string | No | Output format. PNG (default) for text-heavy thumbnails, JPEG for photo-heavy. YouTube accepts JPG, PNG, GIF, BMP under 2MB. (png, jpeg, webp) |
| `negative_prompt` | string | No | Things to avoid in the thumbnail (appended to built-in exclusions for blurry, watermarks, etc.) |
| `guidance_scale` | number | No | How closely to follow the prompt (1-20). Higher = more literal. Model-dependent. |
| `enhance_prompt` | boolean | No | Let the model expand and improve the prompt automatically. |

**Returns:** Thumbnail image(s) at 1280x720, downloadable via asset system, prompt used, YouTube specs, and best practice tips

**Examples:**

*Generate a reaction-style thumbnail for a tech video:*

```json
{
  "topic": "Unboxing the most expensive laptop ever made",
  "style": "reaction",
  "text_overlay": "$15,000 LAPTOP",
  "num_images": 4
}
```

*Before/after thumbnail for a fitness transformation video:*

```json
{
  "topic": "My 90-day body transformation journey",
  "style": "before_after",
  "mood": "inspiring",
  "color_scheme": "warm golden tones"
}
```

*Gaming thumbnail with neon style:*

```json
{
  "topic": "Breaking the world record in Minecraft speedrun",
  "style": "gaming",
  "text_overlay": "WORLD RECORD",
  "color_scheme": "dark with neon green accents",
  "num_images": 6
}
```

*Food thumbnail for a recipe video:*

```json
{
  "topic": "Perfect homemade pizza from scratch in 30 minutes",
  "style": "food",
  "mood": "cozy",
  "additional_details": "Overhead shot of a wood-fired pizza with melted mozzarella and fresh basil"
}
```

## Quick Start

```bash
# Via CLI
TOOLROUTER_API_KEY=tr_live_xxx npx -y toolrouter-mcp call youtube-thumbnails generate_thumbnail --topic Unboxing the most expensive laptop ever made --style reaction --text_overlay $15,000 LAPTOP --num_images 4

# Via REST API
curl -H "Authorization: Bearer tr_live_xxx" \
     -d '{"tool":"youtube-thumbnails","skill":"generate_thumbnail","input":{"topic":"Unboxing the most expensive laptop ever made","style":"reaction","text_overlay":"$15,000 LAPTOP","num_images":4}}' \
     https://api.toolrouter.com/v1/tools/call
```

## Frequently Asked Questions

### What thumbnail styles can I choose from?

`generate_thumbnail` supports reaction, before_after, versus, tutorial, listicle, product, storytime, travel, gaming, and food styles.

### Can I add bold text and brand or face references?

Yes. Use `text_overlay` for the headline and `reference_images` for face consistency or brand assets.

### How many versions can I generate for testing?

Set `num_images` from 1 to 12; 4 to 6 is a good range when you want A/B options.

### What size and format will I get?

Thumbnails come out at 1280x720, and you can choose PNG, JPEG, or WebP. The tool also returns a shareable `image_page` link.

---

## Get Started with ToolRouter

**Already connected?** Call any tool with `use_tool({ tool, skill, input })`. Browse tools with `discover` or visit https://toolrouter.com/llms-full.txt

**New to ToolRouter?** Connect with one command (no API key needed — auto-provisions on first use):

```bash
# MCP (Claude Code, Codex CLI)
claude mcp add toolrouter -- npx -y toolrouter-mcp

# MCP (Cursor, Windsurf, Cline, VS Code, Gemini CLI, Claude Desktop)
{"mcpServers":{"toolrouter":{"command":"npx","args":["-y","toolrouter-mcp"]}}}

# Claude Chat / Claude Cowork / Claude Mobile — add as a connector:
# Settings → Connectors → Add custom connector → URL: https://api.toolrouter.com/mcp

# ChatGPT — add as an app:
# Settings → Apps → Advanced settings → enable Developer mode → Create app → MCP Server URL: https://api.toolrouter.com/mcp

# CLI (works instantly, no restart needed)
npx -y toolrouter-mcp tools                    # browse all tools
npx -y toolrouter-mcp search "seo"             # search by keyword
npx -y toolrouter-mcp call seo analyze_page --url https://example.com
```

Free tools work immediately. For paid tools, visit https://toolrouter.com/claim to add credits.

All platforms: https://toolrouter.com/connect | Full catalog: https://toolrouter.com/llms-full.txt | Docs: https://toolrouter.com/docs