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tech.unravel/mcp-mermaidjs-server

tech.unravel/mcp-mermaidjs-server

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github.com/unravel-teamMedia & Design0Updated 79w ago
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About tech.unravel/mcp-mermaidjs-server

tech.unravel/mcp-mermaidjs-server is an MCP server for saving and rendering MermaidJS diagrams with `mmdc`. It provides separate tools for storing a diagram specification and visualizing it in a chosen format.

Key features

  1. 01Save MermaidJS specifications
  2. 02Render saved diagrams
  3. 03Choose an output format
  4. 04Apply optional CSS

Use cases

  1. 01Save a diagram specification for later rendering
  2. 02Render a saved specification in a selected format

MCP support

The server exposes tools to save diagram specifications and render them for MCP hosts. It requires the `mmdc` CLI to run.

Configuration

Local server config is the same for every client. Copy it into your client’s MCP config file.

mcp.json · Universal config
{
  "mcpServers": {
    "mermaidjs-server": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/inspector"
      ]
    }
  }
}
Run commandnpx -y @modelcontextprotocol/inspector

Local servers need a runtime on your machine (e.g. Node.js 18+). Config file locations differ by client; see your client’s docs.

Packages
npm@modelcontextprotocol/inspector

Tools

No tool list yet

Local servers expose tools only once running on your machine, and the maintainer has not provided a tool list.

Details

From the project README

tech.unravel/mcp-mermaidjs-server

An MCP server for working with MermaidJS, using mmdc.

We create two simple tools:

  • save-diagram
  • visualize-diagram

Using these tools, a host can create beautiful mermaid-js diagrams by:

  • creating an mmd spec and saving it
  • then rendering the saved-spec using specific output format and (optionally) CSS (via access to mmdc)

Usage

Building the Uberjar
  1. make clean && make build
Running the MCP server

PRE-REQUISITES: Needs mmdc CLI to be installed.

Some example commands you can try in Claude Desktop or Inspector:

  1. Create a MermaidJS Sequence Diagram from this spec:
sequenceDiagram
%% See https://mermaidjs.github.io/sequenceDiagram.html

loop everyday D-2 working days 16:00
    ABCD->>DEE: [14:25] BEE (Calculation per TC until ACK becomes OK)

    ABCD->>FGG: BEE (Calculation per TC until ACK becomes OK)
    Note over ABCD,FGG: D-2 weekdays at 14:25
    ABCD->>HII: Projected Authorisations to HII
    Note over ABCD,HII: D-2 weekdays at 16:00
end

loop D-1 before deadline at 7:45
    HII->>DEE: Submission
    Note over HII,DEE: D-1 before deadline
    HII->>FGG: Submission
    Note over HII,FGG: D-1 before deadline
end
Before running the MCP server

Remember:

  1. Replace the full-path to the tech.unravel/mcp-mermaidjs-server Jar with the correct path on your system (i.e. replace /Users/vedang/repo-name below with the correct path)
  2. Specify the full-path to mmdc on your system
In Claude Desktop
    "mcp_mermaidjs_server": {
      "command": "java",
      "args": [
        "-Dclojure.tools.logging.factory=clojure.tools.logging.impl/log4j2-factory",
        "-Dorg.eclipse.jetty.util.log.class=org.eclipse.jetty.util.log.Slf4jLog",
        "-Dlog4j2.contextSelector=org.apache.logging.log4j.core.async.AsyncLoggerContextSelector",
        "-Dlog4j2.configurationFile=log4j2-mcp.xml",
        "-Dbabashka.json.provider=metosin/jsonista",
        "-Dlogging.level=INFO",
        "-Dmcp.vegalite.mmdc_executable=/Users/vedang/.local/share/nvm/v23.11.0/bin/mmdc",
        "-cp",
        "/Users/vedang/repo-name/target/tech.unravel/mcp-mermaidjs-server-1.0.0.jar",
        "tech.unravel.mcp-mermaidjs-server"
      ]
    }
In MCP Inspector

Remember to use the full-path to the tech.unravel/mcp-mermaidjs-server JAR on your system.

npx @modelcontextprotocol/inspector java -Dclojure.tools.logging.factory=clojure.tools.logging.impl/log4j2-factory -Dorg.eclipse.jetty.util.log.class=org.eclipse.jetty.util.log.Slf4jLog -Dlog4j2.contextSelector=org.apache.logging.log4j.core.async.AsyncLoggerContextSelector -Dlog4j2.configurationFile=log4j2-mcp.xml -Dbabashka.json.provider=metosin/jsonista -Dlogging.level=INFO -Dmcp.vegalite.mmdc_executable=/Users/vedang/.local/share/nvm/v23.11.0/bin/mmdc -cp /Users/vedang/repo-name/target/tech.unravel/mcp-mermaidjs-server-1.0.0.jar tech.unravel.mcp-mermaidjs-server

License

Copyright © 2025 Unravel.tech Engineering

Distributed under the MIT License

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New to MCP?

From what the protocol is to installing your first server, these answers cover most first questions.

An open protocol that defines how AI applications connect to external tools and data in a uniform way. Clients talk to the model; MCP servers provide tools, resources and prompt templates. They exchange standard messages, so one server can be reused by many clients.