Civil 3D MCP

Civil 3D MCP 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:

• MCP Server (TypeScript/Node.js) — Communicates with AI assistants via MCP protocol

• 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

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

Setup

1. Build the MCP Server

npm install npm run build

2. Build the Civil 3D Plugin

• Copy the required DLLs from your Civil 3D installation to C_References/ (see C_References/README.md)

• Build the plugin:

cd plugin/Civil3dMcpPlugin dotnet build

3. Load the Plugin in Civil 3D

• Open Civil 3D 2025+

• Type NETLOAD in the command line

• Browse to plugin/Civil3dMcpPlugin/bin/Debug/net8.0-windows/Civil3dMcpPlugin.dll

• 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"] } } }

License

MIT