MCP Kroki Server

An MCP (Model Context Protocol) server for converting Mermaid diagrams to SVG images using Kroki.io.

Features

• Generate URLs for diagrams using Kroki.io

• Download diagrams as SVG, PNG, PDF, or JPEG files

• Support for multiple diagram formats:

  • Mermaid

  • PlantUML

  • Graphviz

  • And many more (see Kroki.io documentation)

Installation

local install

git clone https://github.com/tkoba1974/mcp-kroki.git
cd mcp-kroki
npm install
npm run build

Usage

The server provides two main tools:

1. Generate Diagram URL

Generates a URL for a diagram using Kroki.io.

Parameters:

• type: The diagram type (e.g., "mermaid", "plantuml")

• content: The diagram content in the specified format

• outputFormat (optional): The output format (svg, png, pdf, jpeg, base64)

2. Download Diagram

Downloads a diagram to a local file.

Parameters:

• type: The diagram type (e.g., "mermaid", "plantuml")

• content: The diagram content in the specified format

• outputPath: The path where the diagram should be saved

• outputFormat (optional): The output format (svg, png, pdf, jpeg)

• scale (optional, number, default: 1.0): Scaling factor for the diagram dimensions. Currently only affects SVG output by attempting to modify width/height attributes. Minimum value is 0.1.

Example

// Generate a URL for a Mermaid diagram
const result = await callTool('generate_diagram_url', {
  type: 'mermaid',
  content: 'graph TD; A-->B; B-->C; C-->D;',
  outputFormat: 'svg'
});

// Download a Mermaid diagram
const result = await callTool('download_diagram', {
  type: 'mermaid',
  content: 'graph TD; A-->B; B-->C; C-->D;',
  outputPath: '/path/to/diagram.svg'
});

How It Works

The server uses the Kroki.io API to convert diagrams. The diagram content is compressed and encoded before being sent to Kroki.io.

Usage with Claude Desktop

Add to your Claude Desktop configuration file (claude_desktop_config.json):

local install:

{
  "mcpServers": {
    "mcp-kroki": {
      "command": "node",
      "args": ["/path/to/mcp-kroki/build/index.js"]
    }
  }
}

npx：

{
  "mcpServers": {
    "mcp-kroki": {
      "command": "npx",
      "args": [
        "-y",
        "@tkoba1974/mcp-kroki"
      ]
    }
  }
}

License

MIT