What is Kroki Mcp

Kroki-MCP is a Go-based Model Context Protocol tool that converts textual diagram definitions into images using a Kroki backend. It supports various diagram formats like PlantUML and Mermaid, focusing on simplicity and flexibility.

Use cases

Common use cases include generating diagrams for technical documentation, visualizing workflows, and creating architecture diagrams in software projects.

How to use

To use Kroki-MCP, you can run it from the command line. The default mode is SSE, which streams results. You can specify output formats like PNG, SVG, JPEG, or PDF, and configure the backend Kroki server as needed.

Key features

Key features include support for multiple output formats, flexible configuration options, extensibility for additional diagram types, and integration as an MCP tool for diagram conversion.

Where to use

Kroki-MCP can be used in software development environments where visual representations of diagrams are needed, particularly in documentation, design, and architecture planning.

Kroki-MCP

Kroki-MCP is a command-line tool and MCP integration for converting textual diagrams (e.g., PlantUML, Mermaid) into images using a Kroki backend. It supports both local and remote Kroki servers, with flexible configuration and multiple output formats.

Features

• Modes:
  • SSE: Streams results using Server-Sent Events.
  • STDIO (default): Reads diagram code from stdin and outputs to stdout.
• Output Formats: Supports png (default), svg, jpeg, and pdf.
• Kroki Server: Configurable backend host (default: https://kroki.io).
• Extensible: Easily add support for more diagram types and output formats.
• MCP Integration: Exposes diagram conversion as an MCP tool using github.com/mark3labs/mcp-go.

Usage

# Default (SSE mode, PNG, default Kroki host)
kroki-mcp

# Specify output format
kroki-mcp --format svg

# Use STDIO mode
kroki-mcp --mode stdio --format pdf

# Specify a custom Kroki server
kroki-mcp --kroki-host http://localhost:8000

Configuration

Project Structure

kroki-mcp/
├── cmd/
│   └── kroki-mcp/           # Main CLI and MCP server entry point
├── internal/
│   ├── kroki/               # Kroki client logic (HTTP, formats)
│   ├── config/              # Configuration management (flags, env, files)
│   └── mcp/                 # MCP tool/server integration
├── test/                    # Unit and integration tests
├── Dockerfile               # Docker build file
├── docker-compose.yml       # Docker Compose for dev environment
├── go.mod                   # Go module definition
├── README.md                # Project documentation
└── .gitignore               # Git ignore file

Implementation Steps

1. Scaffold Go project.
2. Implement CLI with default SSE mode, format flags.
3. Implement Kroki client supporting all formats.
4. Implement SSE and STDIO modes.
5. Integrate with mcp-go for MCP tool support.
6. Add error handling and tests.
7. Document usage.

Example: Running as an MCP Server

To run Kroki-MCP as an MCP server from source:

go run github.com/utain/kroki-mcp/cmd/kroki-mcp@latest --mode sse --format png --kroki-host https://kroki.io

You can configure the MCP server in your MCP configuration file as follows:

{
  "mcpServers": {
    "kroki-mcp": {
      "command": "go",
      "args": [
        "run",
        "github.com/utain/kroki-mcp/cmd/kroki-mcp@latest",
        "-m",
        "stdio",
        "-f",
        "png",
        "--kroki-host",
        "https://kroki.io"
      ]
    }
  }
}

Development with Docker

You can use Docker and docker-compose for local development and testing.

Build and Run with Docker

docker build -t kroki-mcp .
docker run --rm -it kroki-mcp --help

Using docker-compose (with local Kroki server)

docker-compose up --build

• This will start both a Kroki server and the kroki-mcp service.
• kroki-mcp will connect to the Kroki server at http://kroki:8000.

Contributing

Please see CONTRIBUTING.md for guidelines on how to contribute to this project.

Changelog

See CHANGELOG.md for release history.

Related Projects

• Kroki
• PlantUML
• Mermaid
• Model Context Protocol (MCP)
• mcp-go

License

This project is licensed under the MIT License.