astah-pro-mcp

takaakit/astah-pro-mcp

3.3

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A local MCP server plugin for Astah Professional that leverages AI to enhance UML modeling capabilities.

UML Modeling Powered by AI Agents — Astah Pro MCP

A local MCP server that runs as a plugin for Astah Professional, a UML modeling tool. This MCP server enables you to do the following and more:

  • Use AI to design systems and represent them as UML models and diagrams in Astah.
  • Ask AI to explain UML models and diagrams in your Astah project.
  • Generate source code from UML models and diagrams in your Astah project, and vice versa.
  • Create UML diagrams in Astah from hand-drawn sketch images.

The videos below show Claude Code designing a simple library management system and drawing a class diagram, a sequence diagram, and an activity diagram. These videos are sped up 5×.

Prompt: Design a simple library management system and draw a class diagram in Astah to represent its structure.
class-diagram.gif

Prompt: Draw a sequence diagram to illustrate the behavior of borrowing a book.
sequence-diagram.gif

Prompt: Draw an activity diagram to illustrate the behavior of returning a book.
activity-diagram.gif


Note: As of October 10, 2025, AI assistants/agents are reasonably good at viewing and editing model information, but their ability to view and edit visual diagram information is still developing.


System Requirements

  • Astah Professional v11.0 or later is required. This does not work with Astah UML.

  • Recommended AI assistants/agents

    • For using the Full (Query + Edit) tool version:
      With over 200 tools exposed in this version, use the AI assistants/agents listed below. Other AI assistants/agents may fail to connect due to the large number of tools, or may connect but only recognize a subset.

      • Claude Desktop
      • Claude Code
      • Codex CLI
      • Gemini CLI

      If you want the AI assistant/agent to edit models or diagrams, use this version.

    • For using the Query-Only tool version:
      This version has exposed around 100 tools, so many AI assistants/agents will likely be able to use this plugin.

      In this version, the AI assistant/agent can only reference information about models and diagrams.


    Note: This MCP server only connects to AI assistants/agents running on the same machine as Astah Professional. According to Astah's terms of use, using Astah via an AI assistant/agent is permitted only if you hold a valid license and access it exclusively for your own use with your licensed Astah. Allowing a non-licensed third party to operate Astah via such an assistant/agent is strictly prohibited.
    For details, please refer to the FAQ (English / Japanese) or contact Change Vision (the developer of Astah) directly.


Supported Diagram Types

This MCP server can view and edit the following diagrams (with more to come):

  • Class Diagram
  • Sequence Diagram
  • Activity Diagram
  • State Machine Diagram
  • Usecase Diagram
  • Communication Diagram (for query only; editing is not possible)

Installation

Install Astah Professional

Download from here and install.

Install the astah-pro-mcp Plugin

Download the plugin JAR file (astah-pro-mcp-x.x.x.jar), drop it into Astah, then restart Astah (see here). After restarting, if you see an 'mcp' tab in Astah's extensions view, the installation was successful.

mcp tab

AI Assistant/Agent Settings

To use the Full tool version, specify port 8888; to use the Query-Only tool version, specify port 8889. And, use 127.0.0.1 instead of localhost. Connections to localhost will fail.

Claude Desktop
claude_desktop_config.json 
{
  "mcpServers": {
    "astah-pro-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote@latest",
        "http://127.0.0.1:8888/mcp",
        "--allow-http"
      ]
    }
  }
}

Note: As of October 10, 2025, Streamable HTTP connections to a local MCP server don't seem to work well in Claude Desktop. Use a bridge such as mcp-remote, which requires Node.js v20 or later.

Claude Code
.mcp.json 
{
  "mcpServers": {
    "astah-pro-mcp": {
      "type": "http",
      "url": "http://127.0.0.1:8888/mcp"
    }
  }
}

Or run this command:

claude mcp add --transport http --scope project astah-pro-mcp http://127.0.0.1:8888/mcp

See here for information on the --scope flag.

Note: If you are using Claude Code on WSL2 in Windows, you need to allow WSL to access Windows' 127.0.0.1. So, see here and consider enabling Mirrored mode.

Codex CLI
config.toml 
[mcp_servers.astah-pro-mcp]
command = "npx"
args = ["mcp-remote@latest", "http://127.0.0.1:8888/mcp", "--allow-http"]

Note: As of October 10, 2025, Streamable HTTP connections to a local MCP server don't seem to work well in Codex CLI. Use a bridge such as mcp-remote, which requires Node.js v20 or later.

Note: If you are using Codex CLI on WSL2 in Windows, you need to allow WSL to access Windows' 127.0.0.1. So, see here and consider enabling Mirrored mode.

Gemini CLI
settings.json 
{
  "mcpServers": {
    "httpServer": {
      "httpUrl": "http://127.0.0.1:8888/mcp",
      "timeout": 5000
    }
  }
}
Cursor
mcp.json 
{
  "mcpServers": {
    "astah-pro-mcp": {
      "type": "http",
      "url": "http://127.0.0.1:8889/mcp"
    }
  }
}
VSCode (Copilot)
mcp.json 
{
  "servers": {
    "astah-pro-mcp": {
      "type": "http",
      "url": "http://127.0.0.1:8889/mcp"
    }
  }
}
Antigravity
mcp_config.json 
{
  "mcpServers": {
    "astah-pro-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-remote@latest",
        "http://127.0.0.1:8889/mcp",
        "--allow-http"
      ],
      "env": {}
    }
  }
}

Note: As of December 5, 2025, Streamable HTTP connections to a local MCP server don't seem to work well in Antigravity. Use a bridge such as mcp-remote, which requires Node.js v20 or later.


How to Use

  1. Start Astah (starting Astah also starts the MCP server).
    Some AI assistants/agents try to connect to the MCP server on startup, so start Astah first.

  2. Start the AI assistant/agent.
    On the first connection to the MCP server, you will be asked to confirm. Review the details and click 'Connect'.
    Connection Request

  3. Send prompts to the AI assistant/agent.

If you want to disable this plugin in Astah, click [Plugin] > [Installed Plugin], select the Astah Pro MCP entry in the plugin list dialog, click Disable, and then restart Astah.


Troubleshooting: If Claude Desktop cannot connect to the MCP server, completely quit Claude Desktop (e.g., end the 'Claude' process in Task Manager), then restart it.


Build & Test

If you want to build and test locally:

  1. Set up your Astah plugin development environment (see here).

  2. Build:

    astah-build

  3. Run tests (update astahPath to match your Astah Professional installation path):

    Run all tests on Windows 11:

    astah-mvn test -DastahPath="C:\Program Files\astah-professional"

    Run specific tests on Windows 11:

    astah-mvn test -DastahPath="C:\Program Files\astah-professional" -Dtest="**/editor/*Test"

Considerations

Experimental Status

This project is currently experimental. The design and implementation may undergo breaking changes.

Confidential Risk

Astah project data and logs will be shared with the AI assistant/agent. For Astah projects that contain confidential information, either refrain from using this MCP server or use it only with appropriate safeguards (e.g., enabling opt-out settings for AI assistants/agents).

Backups Recommended

Because this MCP server edits models and diagrams, we recommend committing your Astah project to a Git repository or making copies before and during use so you can revert if necessary.

Feature Limitations

Some model or diagram information (e.g., certain properties) cannot be viewed or edited via the provided tool functions. Use the Astah GUI directly for those.

Costs

This MCP server prioritizes providing the information AI assistants/agents need and does not implement token-saving measures. We recommend using AI assistants/agents on a flat-rate plan rather than pay-as-you-go.

AI Limitations

As with source code, AI assistants/agents can make mistakes or misinterpret UML models and diagrams.


License

Some tool functions provided by this MCP server return excerpts from the OMG UML 2.5.1 and OMG SysML 1.7 specifications. These specifications are licensed as stated at the beginning of each document. When a tool function returns such material, it explicitly indicates that it is an excerpt.

All other source code is copyrighted by Takaaki Teshima and released under the MIT-0 license.
License: MIT-0


Got a feature request or found a bug?

Please open an issue. Because this project is experimental phase and may introduce breaking changes, we aren't accepting pull requests until the design and implementation stabilize. Thank you for your understanding.


Need support?

If you need private support, contact takaaki.teshima.dev [at] gmail.com (replace [at] with @). It could become a paid project; I may still be able to support you/it.