Civil 3D Server

An MCP (Model Context Protocol) server that enables AI assistants (Claude, Cline, etc.) to interact with Autodesk Civil 3D through natural language.

Architecture

┌─────────────────┐     stdio      ┌──────────────────┐     TCP/JSON-RPC    ┌──────────────────┐
│   AI Assistant   │ ◄────────────► │  MCP Server (TS) │ ◄──────────────────► │  Civil 3D Plugin │
│ (Claude, Cline)  │               │   Node.js         │     port 8080       │   (.NET 8.0 C#)  │
└─────────────────┘               └──────────────────┘                      └──────────────────┘
                                                                                     │
                                                                              Civil 3D API
                                                                            (Surfaces, Alignments,
                                                                             Points, Corridors...)

The system has two components:

1. MCP Server (TypeScript/Node.js) — Communicates with AI assistants via MCP protocol
2. Civil 3D Plugin (C# .NET 8.0) — Runs inside Civil 3D and executes API commands

Available Tools

Tool	Actions	Description
civil3d_health	health	Check plugin connectivity
civil3d_drawing	info, settings, save, undo, redo, list_object_types, get_selected	Drawing operations
civil3d_surface	list, get, get_elevation, get_statistics, create, delete, add_points, add_breakline, add_boundary, extract_contours, compute_volume	Surface management
civil3d_alignment	list, get, create, delete, station_to_point, point_to_station	Alignment operations
civil3d_profile	list, get, get_elevation, create_from_surface, create_layout, delete	Profile management
civil3d_corridor	list, get, rebuild, get_surfaces, get_feature_lines, compute_volumes	Corridor operations
civil3d_pipe	list_networks, get_network, get_pipe, get_structure, create_network, add_pipe, add_structure, check_interference	Pipe networks
civil3d_point	list, get, create, delete, list_groups, import	COGO points
civil3d_geometry	create_line, create_polyline, create_3d_polyline, create_text, create_mtext	Basic AutoCAD geometry

Setup

1. Build the MCP Server

npm install
npm run build

2. Build the Civil 3D Plugin

1. Copy the required DLLs from your Civil 3D installation to C_References/ (see C_References/README.md)
2. Build the plugin:

cd plugin/Civil3dMcpPlugin
dotnet build

3. Load the Plugin in Civil 3D

1. Open Civil 3D 2025+
2. Type NETLOAD in the command line
3. Browse to plugin/Civil3dMcpPlugin/bin/Debug/net8.0-windows/Civil3dMcpPlugin.dll
4. The plugin starts automatically. Use C3DMCPSTATUS to verify.

4. Configure Your AI Assistant

Claude Desktop — Add to claude_desktop_config.json:

{
  "mcpServers": {
    "civil3d": {
      "command": "node",
      "args": ["/path/to/civil3d-mcp/build/index.js"]
    }
  }
}

Environment Variables

Variable	Default	Description
CIVIL3D_HOST	localhost	Civil 3D plugin host
CIVIL3D_PORT	8080	Civil 3D plugin port
CIVIL3D_CONNECT_TIMEOUT	5000	Connection timeout (ms)
CIVIL3D_COMMAND_TIMEOUT	120000	Command execution timeout (ms)
LOG_LEVEL	info	Log level (debug, info, warn, error)

Plugin Commands

Command	Description
C3DMCPSTART	Start the TCP listener
C3DMCPSTOP	Stop the TCP listener
C3DMCPSTATUS	Check listener status

License

MIT