Claude Pascal MCP Server

An MCP (Model Context Protocol) server that lets Claude compile, run, and interact with Pascal/Delphi desktop applications. Supports Free Pascal (fpc), Delphi 32-bit (dcc32), and Delphi 64-bit (dcc64) compilers.

Features

• Compiler Detection — automatically finds Pascal compilers on your system (PATH + known install locations)

• Compile — compile single-file Pascal source or multi-file Delphi projects

• Run — compile and execute console programs, capturing output

• Launch GUI Apps — compile and launch VCL/FMX applications in background (without stealing focus)

• Project Templates — generate proper Delphi project structure (DPR + PAS + DFM) automatically

• Form Parser — read and understand DFM/FMX/LFM form files

• Window Screenshots — capture running desktop app windows (non-intrusive, no focus stealing)

• Windows App Interaction — click, type text, and send keyboard shortcuts to desktop app windows

• Android Device Interaction — full ADB support: screenshots, tap, swipe, type, key events, app management, file transfer

• IDE Observer — capture RAD Studio/Delphi/Lazarus IDE screenshots and read compiler errors

• Preview Bridge — live preview of running Pascal apps through Claude's preview system

• FPC Installer — download and install Free Pascal if no compiler is available

Tools

Preview Bridge

The preview bridge lets Claude see and interact with running Pascal desktop applications through its web-based preview system. It serves live screenshots of desktop app windows as a web page.

How it works

Claude Preview Tools (preview_start, preview_screenshot, preview_click)
        | HTTP
        v
Preview Bridge Server (Python/Starlette)
   /               -> HTML page with live screenshot viewer
   /api/screenshot  -> PNG of target window
   /api/controls    -> enumerate child controls with positions
   /api/click       -> click at coordinates or by control hwnd
   /api/type        -> send keystrokes to target window
   /api/move        -> move window to screen position
   /api/resize      -> resize window
        | Win32 PrintWindow API
        v
Running Pascal Desktop Application

API Endpoints

Click Methods

The click endpoint supports three modes, from most to least reliable:

1. Direct control click ({"hwnd": "12345"}) — sends BM_CLICK directly to a control handle. Works regardless of DPI, monitors, or foreground state. Get hwnds from /api/controls.

2. Client-area coordinates ({"x": 200, "y": 142, "client": true}) — uses Win32 ClientToScreen for proper DPI handling.

3. Window-relative coordinates ({"x": 312, "y": 261}) — raw coordinates in the screenshot image space.

Windows App Interaction

The app_click, app_type, and app_key tools let Claude interact with running Windows desktop applications.

Workflow

1. Take a screenshot with screenshot_app to see the current UI

2. Identify pixel coordinates of the target element (button, text field, etc.)

3. Use app_click with those coordinates to click

4. Use app_type to enter text into a focused field

5. Use app_key to send keyboard shortcuts (enter, ctrl+a, alt+f4, etc.)

Clicks use PostMessage with automatic child window targeting, so they reach the correct control. Typing and key events use SendInput for full Unicode and modifier support.

Android Device Interaction (ADB)

Full Android device interaction via ADB. All tools accept an optional device serial number — auto-selects when only one device is connected.

Device Management

• adb_devices — list connected devices with model, Android version, screen size

• adb_device_info — detailed info for a specific device

Screenshots and UI Automation

• adb_screenshot — capture the device screen

• adb_tap / adb_swipe — touch interaction at pixel coordinates

• adb_type_text — type text (auto-escapes for adb shell)

• adb_key — send key events with aliases: home, back, enter, menu, power, volume_up, volume_down, tab, delete, space, escape, app_switch

App Management

• adb_install — install APK files

• adb_list_packages — list installed packages (with optional filter)

• adb_launch_app — launch an app by package name

• adb_stop_app — force-stop an app

File Transfer

• adb_push — push files from PC to device

• adb_pull — pull files from device to PC

Project Templates

The compile_delphi_project tool generates proper Delphi project structure automatically. You specify components and events, and it creates the correct DPR, PAS, and DFM files.

Templates automatically handle:

• Modern Delphi (RAD Studio): namespaced units (Vcl.Forms, System.SysUtils)

• Legacy Delphi (Delphi 7): non-namespaced units (Forms, SysUtils)

• Form definitions (DFM) with proper component declarations

• Event handler wiring between DFM and PAS files

Example

compile_delphi_project(
  project_name="HelloWorld",
  form_caption="My App",
  components='[{"type": "TButton", "name": "btnHello", "caption": "Click Me",
                "left": 100, "top": 100, "width": 120, "height": 35,
                "event": "btnHelloClick"}]',
  events='[{"name": "btnHelloClick", "body": "ShowMessage(\'Hello!\');"}]',
  compiler="C:\\Path\\To\\dcc64.exe"
)

This generates:

• HelloWorld.dpr — project file with proper uses clause

• uMain.pas — unit with form class, component declarations, event handlers

• uMain.dfm — form definition with component properties

Installation

Prerequisites

• Python 3.11+

• uv package manager

• A Pascal compiler (Free Pascal, Delphi, or RAD Studio)

Option 1 — Run from PyPI (recommended)

Once a release is published to PyPI, no clone is needed:

uvx --from claude-pascal-mcp pascal-mcp

Option 2 — Run straight from GitHub (no PyPI required)

uvx --from git+https://github.com/tina4stack/claude-pascal-mcp pascal-mcp

Pin to a tag for reproducibility: git+https://github.com/tina4stack/claude-pascal-mcp@v0.1.0.

Option 3 — Local development clone

git clone https://github.com/tina4stack/claude-pascal-mcp.git
cd claude-pascal-mcp

# Install dependencies
uv sync

# Run the MCP server (stdio mode)
uv run pascal-mcp

# Run the preview bridge (HTTP mode)
uv run pascal-preview

Register with Claude Code

PyPI install:

claude mcp add --transport stdio pascal-dev -- uvx --from claude-pascal-mcp pascal-mcp

Git install:

claude mcp add --transport stdio pascal-dev -- uvx --from git+https://github.com/tina4stack/claude-pascal-mcp pascal-mcp

Local clone:

claude mcp add --transport stdio pascal-dev -- uv run --directory /path/to/claude-pascal-mcp pascal-mcp

Or add to your project's .mcp.json — pick the form that matches how you installed:

{
  "mcpServers": {
    "pascal-dev": {
      "command": "uvx",
      "args": ["--from", "claude-pascal-mcp", "pascal-mcp"]
    }
  }
}

{
  "mcpServers": {
    "pascal-dev": {
      "command": "uvx",
      "args": ["--from", "git+https://github.com/tina4stack/claude-pascal-mcp", "pascal-mcp"]
    }
  }
}

{
  "mcpServers": {
    "pascal-dev": {
      "command": "uv",
      "args": ["run", "--directory", "/path/to/claude-pascal-mcp", "pascal-mcp"]
    }
  }
}

Register with Claude Desktop

Add to your claude_desktop_config.json (pick the form matching your install):

{
  "mcpServers": {
    "pascal-dev": {
      "command": "uvx",
      "args": ["--from", "claude-pascal-mcp", "pascal-mcp"]
    }
  }
}

{
  "mcpServers": {
    "pascal-dev": {
      "command": "uv",
      "args": ["run", "--directory", "C:/path/to/claude-pascal-mcp", "pascal-mcp"]
    }
  }
}

Releasing

Maintainer notes — cutting a new release publishes to PyPI automatically.

1. Bump version in pyproject.toml.

2. Commit and tag: git tag v0.1.0 && git push origin v0.1.0.

3. GitHub Actions (.github/workflows/publish.yml) builds the sdist + wheel, publishes to PyPI via Trusted Publishing, and attaches the artifacts to a GitHub Release.

One-time PyPI Trusted Publisher setup (required before the first release):

• Create the project on pypi.org (or reserve it via a first manual uv publish).

• Under Project → Publishing → Add a new publisher, configure GitHub Actions:

  • Owner: tina4stack

  • Repository: claude-pascal-mcp

  • Workflow: publish.yml

  • Environment: pypi

• In the GitHub repo, create an environment named pypi (Settings → Environments).

No API tokens needed — OIDC handles auth.

Preview Bridge Setup

Add to .claude/launch.json in your project root:

{
  "version": "0.0.1",
  "configurations": [
    {
      "name": "pascal-preview",
      "runtimeExecutable": "/path/to/claude-pascal-mcp/.venv/Scripts/pythonw.exe",
      "runtimeArgs": ["-m", "pascal_mcp.preview_bridge"],
      "port": 18080,
      "autoPort": true
    }
  ]
}

Then in Claude Code, use preview_start("pascal-preview") to open the preview panel.

Supported Compilers

The server automatically detects compilers in this priority order:

1. Free Pascal (fpc) — open source, cross-platform

2. Delphi 64-bit (dcc64) — RAD Studio command-line compiler

3. Delphi 32-bit (dcc32) — RAD Studio / Delphi 7 command-line compiler

You can also specify a full path to any compiler executable:

compile_pascal(source, compiler="C:\\Program Files (x86)\\Embarcadero\\Studio\\37.0\\bin\\dcc64.exe")

Detection checks the system PATH first, then known installation directories:

• C:\FPC\*\bin\*\fpc.exe

• C:\Lazarus\fpc\*\bin\*\fpc.exe

• C:\Program Files (x86)\Embarcadero\Studio\*\bin\dcc*.exe

License

MIT