Mermaid MCP Server

@peng-shawn

About Mermaid MCP Server

A Model Context Protocol (MCP) server that converts Mermaid diagrams to PNG images

Config

Add this server to your MCP-compatible client using the configuration below.

{
  "mcpServers": {
    "mermaid-mcp-server": {
      "command": "npx",
      "args": [
        "tsc"
      ]
    }
  }
}

Tools

No tools detected

Fetch the live tool list by running this server in a temporary sandbox using the button above.

Overview

What is Mermaid MCP Server?

Mermaid MCP Server converts Mermaid diagram code into PNG images or SVG files. It uses Puppeteer for headless browser rendering and implements the Model Context Protocol (MCP) so AI assistants and other applications can generate visual diagrams from textual descriptions.

How to use Mermaid MCP Server?

Run the server with npx -y @peng-shawn/mermaid-mcp-server. Configure it as an MCP tool in Claude Desktop, Cursor, or Cline using the provided JSON entries. The server exposes a single generate tool that accepts parameters code, theme, backgroundColor, outputFormat, name, and folder. Set the environment variable CONTENT_IMAGE_SUPPORTED to true (default) for inline images or false to save to disk.

Key features of Mermaid MCP Server

Converts Mermaid code to PNG or SVG
Supports four diagram themes: default, forest, dark, neutral
Customizable background colors
Uses Puppeteer for high‑quality rendering
Implements MCP protocol for seamless AI integration
Returns images inline or saves them to disk

Use cases of Mermaid MCP Server

Generate flowcharts, sequence diagrams, and class diagrams in AI assistants
Create diagrams with specific themes and background colors
Save diagram files to disk when inline images are not supported (e.g., Cursor)
Automate diagram generation in MCP‑compatible tools

FAQ from Mermaid MCP Server

Does Claude desktop already support Mermaid via canvas?

Yes, but it does not support the theme and backgroundColor options. A dedicated server makes it easier to create Mermaid diagrams with different MCP clients.

Why do I need to set `CONTENT_IMAGE_SUPPORTED=false` when using with Cursor?

Cursor does not support inline images in responses yet. Setting the variable to false saves the diagram to disk and returns the file path.

What are the runtime dependencies?

The server requires Node.js (to run the npx command) and relies on Puppeteer’s bundled Chromium or a system‑installed Chrome/Chromium for headless rendering.

How are generated images returned or stored?

When CONTENT_IMAGE_SUPPORTED=true (default), the image or SVG is returned inline in the MCP response. When false, the file is saved to the specified folder and the file path is returned.

Which transport does the server use?

The server communicates over stdio using the MCP protocol. It can be tested and debugged with the MCP Inspector (npx @modelcontextprotocol/inspector).

Frequently asked questions

Does Claude desktop already support Mermaid via canvas?

Yes, but it does not support the `theme` and `backgroundColor` options. A dedicated server makes it easier to create Mermaid diagrams with different MCP clients.

Why do I need to set `CONTENT_IMAGE_SUPPORTED=false` when using with Cursor?

Cursor does not support inline images in responses yet. Setting the variable to `false` saves the diagram to disk and returns the file path.

What are the runtime dependencies?

The server requires Node.js (to run the npx command) and relies on Puppeteer’s bundled Chromium or a system‑installed Chrome/Chromium for headless rendering.

How are generated images returned or stored?

When `CONTENT_IMAGE_SUPPORTED=true` (default), the image or SVG is returned inline in the MCP response. When `false`, the file is saved to the specified folder and the file path is returned.

Which transport does the server use?

The server communicates over stdio using the MCP protocol. It can be tested and debugged with the MCP Inspector (`npx @modelcontextprotocol/inspector`).

Comments

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