Viralth for agents and developers

1. Get an API key

Create it in your Dashboard. There is one active key per account, it is shown once, and replacing it revokes the old one immediately. Keep it out of code you share.

2. Connect the MCP server

Viralth speaks the Model Context Protocol over HTTP. Point your client at this URL and send your key in the Authorization header.

https://viralth.com/api/mcp

Claude Code

claude mcp add --transport http viralth https://viralth.com/api/mcp \
  --header "Authorization: Bearer YOUR_KEY"

Cursor (~/.cursor/mcp.json)

{
  "mcpServers": {
    "viralth": {
      "url": "https://viralth.com/api/mcp",
      "headers": { "Authorization": "Bearer YOUR_KEY" }
    }
  }
}

Claude Desktop (claude_desktop_config.json)

Claude Desktop runs remote servers that need a header through mcp-remote, which needs Node.js installed.

{
  "mcpServers": {
    "viralth": {
      "command": "npx",
      "args": ["-y", "mcp-remote", "https://viralth.com/api/mcp",
               "--header", "Authorization:${VIRALTH_AUTH}"],
      "env": { "VIRALTH_AUTH": "Bearer YOUR_KEY" }
    }
  }
}

Then ask: “Make me a thumbnail for this video, in Spanish and English.” You get both images back, and one credit is used.

Tools

• generate_thumbnail1 credit per image

  Generates 1 to 4 thumbnails from a title, without a photo of anyone, with the headline as editable text. Optionally delivers it in several languages at once.

• localize_thumbnailFree

  Translates an existing thumbnail's text into Spanish, English, Portuguese, French, German or Italian. Same artwork, one image per language.

• edit_textFree

  Changes the text, font, colour or size of a text layer and returns the updated image.

• list_thumbnailsFree

  Your most recent thumbnails, with the id each tool needs.

• get_creditsFree

  How many credits are left.

• list_youtube_videosFree

  The recent uploads of the YouTube channel you connected in the Dashboard.

• publish_to_youtubeFree

  Sets one of those videos' thumbnail, in one language. It changes the live video, so agents are told to confirm first.

REST API

The MCP tools call the same endpoints the Studio uses, and those accept your key too. With "textMode": "layers" you get the artwork without text and a generationId; leave it out and the headline is painted into the image.

curl https://viralth.com/api/generate-thumbnail \
  -H "Authorization: Bearer YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"variantId":"A","config":{"title":"I tested every cheap keyboard",
       "visualStyle":"hyperrealistic","subjectPosition":"Right",
       "identityStrength":90,"faceEmotion":"original",
       "subjectMode":"faceless","textMode":"layers","format":"youtube"}}'

Limits, plainly

• Each generated image costs 1 credit, exactly as in the Studio, and a failed generation is refunded.
• Up to 10 image generations and 20 other requests per minute per account.
• The MCP server makes thumbnails without a person in them. Using your own face needs the Studio for now.
• Sign-in is by API key only. Connectors that only support OAuth, such as ChatGPT's, are not supported yet.