LABSCO SUMMARY

A diagram the model can fix, because it is told when the syntax is wrong.

Validation is the quiet feature here. Without it a malformed diagram comes back as a broken picture; with it the model gets an error it can act on and tries again.

What it is

A diagram generator that renders Mermaid on the server side. Full Mermaid syntax is supported, and the render step validates the input so a model that gets the syntax wrong is told, rather than handed a broken image.

What you get

Every Mermaid feature and syntax, with backgroundColor and theme configurable so a model can produce rich style settings
Six output types: base64, svg, mermaid, file — which saves a PNG to disk for agents that work with files — and the remote-friendly svg_url and png_url that share through public mermaid.ink links
Syntax validation, which is what lets a model iterate over several rounds towards correct output and correct graphics
Three transports selected with --transport: stdio by default, sse, and streamable, with --port and --endpoint to place them

Requirements

Nothing to install for the common case — configure your client with npx -y mcp-mermaid, using the cmd /c prefix on Windows. For a long-running server, npm install -g mcp-mermaid then mcp-mermaid -t sse or mcp-mermaid -t streamable; the SSE endpoint defaults to /sse on port 3033 and the streamable endpoint to /mcp, with the local development scripts using 1122 for streamable. A Docker image, susuperli/mcp-mermaid:latest, is published for both transports. It is also reachable through hosted platforms including aliyun, modelscope, glama.ai and smithery.ai over HTTP or SSE. MIT licensed.

Setup effort

One command — npm install -g mcp-mermaid

See installation options

USE CASES

01

Getting a diagram out of a conversation

Describe the flow and get the rendered result back, with background colour and theme set from the same request.

02

Putting the image in a document

Ask for the file output type and a PNG is written to disk, ready to attach — no copy-and-paste from a preview.

03

Sharing a diagram with someone else

The URL output types return public links, which travel better than a base64 blob in a chat.

04

Keeping the source, not just the picture

The mermaid output type returns the diagram definition itself, so it can be checked into a repository and re-rendered later.

05

Running it as a shared service

Install globally or run the Docker image with the SSE or streamable transport, and point several clients at the same endpoint.

BEFORE YOU INSTALL

What to know first

Requires

npx on PATH

Where it runs

All 4 documented clients run the server on your machine.

INSTALLATION

Connect your client

Server setup

TERMINAL

npm install -g mcp-mermaid

MCP Clients

Claude Desktop, Cline, Cherry Studio

JSON

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

VS Code

VS CODE · JSON

{
  "servers": {
    "mcp-mermaid": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-mermaid"
      ]
    }
  }
}

Mermaid