mcp-swing-17

mcp-swing-17

MCP server and Java agent for automating Swing and JavaFX desktop applications, built for Java 17. Fork of Swing MCP.

• Version: 1.5.0-java17
• Upstream commit: abfacfa
• License: MIT (see LICENSE)
• Usage guide: USAGE.md

Contents

dist/mcp-swing-17-server.jar    MCP server (stdio)
dist/mcp-swing-17-agent.jar     Java agent loaded into the target JVM
dist/*.mcpb                      MCPB bundle for one-click clients
build.ps1                       Windows build (JDK 17)
build.sh                        Linux/macOS build
mcp-swing-17-server/            server sources
mcp-swing-17-agent/             agent sources
mcp-swing-17-common/            shared classes

Build

powershell -NoProfile -ExecutionPolicy Bypass -File build.ps1

Requires JDK 17. Maven 3.9.9 is downloaded into .build/ on first use.

On Linux/macOS:

./build.sh

or:

mvn -s maven-settings.xml -DskipTests package

Run

SWING_MCP_AGENT_JAR=<path>/dist/mcp-swing-17-agent.jar
java -jar <path>/dist/mcp-swing-17-server.jar

The server uses stdio and is normally started by an MCP client. The agent attaches to an already running Java application by PID through attach_to_app.

{
  "mcpServers": {
    "mcp-swing-17": {
      "command": "java",
      "args": ["-jar", "<path>/dist/mcp-swing-17-server.jar"],
      "env": {
        "SWING_MCP_AGENT_JAR": "<path>/dist/mcp-swing-17-agent.jar"
      }
    }
  }
}

Differences from upstream

1. Java 17 instead of Java 21: virtual threads replaced with a regular executor.
2. Removed the Java 17-incompatible JMenu instanceof JMenuItem pattern.
3. Replaced List.getFirst() with get(0).
4. Relocated the agent's Jackson package so the target application's Jackson cannot shadow it.
5. java.version=17, JavaFX 17.
6. Real-mouse robot input is disabled by default.
7. close_window closes only the focused dialog unless a windowIndex is passed explicitly.

Security

• the agent listens on loopback only;
• keep evaluate_java disabled;
• use as a development/testing tool;
• do not expose the agent port or the response-file token.