AutoCAD LT AutoLISP MCP Server

This MCP server enables natural language control of AutoCAD LT 2024/2025 through AutoLISP code generation and execution. It bridges Claude or other LLM clients with AutoCAD LT for creating engineering drawings, P&ID diagrams, and technical documentation through conversational prompts.

🚀 Key Features

Core Drawing Operations

• Generates and executes AutoLISP code in AutoCAD LT 2024+
• Creates basic shapes (lines, circles, polylines, text)
• Handles block insertion with comprehensive attribute management
• Supports advanced geometry (arcs, ellipses, rectangles)
• Provides robust layer creation and management
• Creates hatches and dimensions for technical drawings

P&ID and Process Engineering (NEW)

• CTO Library Integration: Complete access to CAD Tools Online P&ID Symbol Library (600+ ISA 5.1-2009 standard symbols)
• Intelligent Attribute Handling: Proper block attributes for equipment schedules and valve lists
• Process Equipment: Pumps, valves, tanks, instruments, and process equipment
• Standard Annotations: Equipment tags, descriptions, and line numbers
• Layer Management: Industry-standard P&ID layer organization

Performance Optimizations

• Fast Mode: Optimized execution with minimal delays (80% speed improvement)
• Batch Operations: Create multiple objects in single operations
• Clipboard Integration: Efficient large script execution
• Smart Loading: Essential LISP files only for faster startup

📋 Prerequisites

• AutoCAD LT 2024 or newer (with AutoLISP support)
• Python 3.10 or higher
• Claude Desktop or other MCP client application
• Optional: CAD Tools Online P&ID Symbol Library (for full P&ID functionality)

🛠️ Setup Instructions

1. Install Dependencies

git clone https://github.com/hvkshetry/autocad-mcp.git
cd autocad-mcp
python -m venv venv
venv\Scripts\activate
pip install -r requirements.txt

2. Configure Claude Desktop

For users WITH CTO Library:

{
  "mcpServers": {
    "autocad-mcp": {
      "command": "path\\to\\autocad-mcp\\venv\\Scripts\\python.exe",
      "args": ["path\\to\\autocad-mcp\\server_lisp_fast.py"]
    }
  }
}

For users WITHOUT CTO Library:

{
  "mcpServers": {
    "autocad-mcp": {
      "command": "path\\to\\autocad-mcp\\venv\\Scripts\\python.exe",
      "args": ["path\\to\\autocad-mcp\\server_lisp.py"]
    }
  }
}

3. CTO Library Setup (Optional but Recommended)

If you have the CAD Tools Online P&ID Library:

1. Install the CTO library to C:\PIDv4-CTO\
2. Verify the following directories exist:
   • C:\PIDv4-CTO\VALVES\
   • C:\PIDv4-CTO\EQUIPMENT\
   • C:\PIDv4-CTO\PUMPS-BLOWERS\
   • C:\PIDv4-CTO\TANKS\
   • (and other standard categories)

If you DON'T have the CTO Library:

• Use server_lisp.py instead of server_lisp_fast.py
• P&ID tools will not work, but all basic drawing operations remain available
• You can still create custom blocks and use standard AutoCAD functionality

4. Start AutoCAD and Server

1. Launch AutoCAD LT

   • Create or open a drawing
   • Ensure command line is visible

2. Start the Server

   # For users with CTO library (recommended)
   start_fast_server.bat
   
   # For users without CTO library
   start_lisp_server.bat
   

3. Test the Connection

   test_connection.bat
   

🔧 Available Tools

Basic Drawing Tools

• create_line: Draw lines between points
• create_circle: Create circles with center and radius
• create_text: Add text labels with rotation support
• create_polyline: Create polylines from point series
• create_rectangle: Create rectangles from corner points
• batch_create_lines: Create multiple lines efficiently
• batch_create_circles: Create multiple circles efficiently
• batch_create_texts: Create multiple text entities efficiently

Block and Layer Management

• insert_block: Insert blocks with attributes and positioning
• set_layer_properties: Create/modify layers with full properties
• move_last_entity: Move recently created entities
• update_block_attribute: Modify block attributes after insertion

P&ID and Process Tools (CTO Library Required)

• setup_pid_layers: Create standard P&ID drawing layers
• insert_pid_symbol: Insert any symbol from CTO library
• insert_pid_equipment_with_attribs: Insert equipment with proper attributes
• insert_valve_with_attributes: Insert valves with CTO attributes
• insert_equipment_tag: Add equipment identification tags
• insert_equipment_description: Add equipment description blocks
• insert_line_number_tag: Add process line identification
• draw_process_line: Draw process piping between points
• connect_equipment: Connect equipment with orthogonal routing
• add_flow_arrow: Add directional flow indicators

Advanced Operations

• create_arc: Create arcs with center, radius, and angles
• create_ellipse: Create ellipses with major axis and ratio
• create_mtext: Add multiline formatted text
• create_linear_dimension: Add linear dimensions
• create_hatch: Add hatching to closed areas
• list_pid_symbols: List available symbols by category

📖 Usage Examples

Basic Drawing

"Draw a line from (0,0) to (100,100)"
"Create a circle at (50,50) with radius 25"
"Add text 'Equipment Room' at position (75,125)"

P&ID Creation (with CTO Library)

"Set up P&ID layers for a new drawing"
"Insert a centrifugal pump at (100,100) with tag P-101"
"Add a gate valve at (150,100) with size 6 inches and tag V-201"
"Connect the pump P-101 to valve V-201 with process piping"
"Add equipment tag P-101 above the pump"

Process Flow Creation

"Create a wastewater treatment process with screening, primary clarifier, aeration basin, and secondary clarifier"
"Insert a clarifier at (200,100) with equipment number CL-301"
"Add line number 8"-WW-001 to the main process line"

Batch Operations

"Create 10 circles in a grid pattern with centers every 50 units"
"Draw process lines connecting all equipment in sequence"
"Add equipment tags for all pumps with sequential numbering"

🚧 Configuration for Users Without CTO Library

If you don't have the CAD Tools Online library, you can still use this MCP server effectively:

1. Use the Standard Server

Replace the server command with:

"args": ["path\\to\\autocad-mcp\\server_lisp.py"]

2. Modify P&ID Tool Calls

The following tools will not work without CTO library:

• insert_pid_symbol
• insert_pid_equipment_with_attribs
• insert_valve_with_attributes
• list_pid_symbols

3. Alternative Approaches

Instead of CTO symbols, you can:

• Use standard AutoCAD blocks
• Create simple geometric representations
• Use text labels for equipment identification
• Import your own symbol library

4. Example Alternative Usage

"Draw a circle to represent a pump at (100,100)"
"Add text 'P-101 Centrifugal Pump' next to it"
"Create a rectangle for a tank at (200,100)"
"Connect them with a line for piping"

📁 LISP Library Structure

The server loads these LISP files for functionality:

File	Purpose	Dependencies
error_handling.lsp	Base error handling and validation	None (load first)
basic_shapes.lsp	Core drawing functions	error_handling.lsp
batch_operations.lsp	Batch creation tools	basic_shapes.lsp
drafting_helpers.lsp	Block and layer management	basic_shapes.lsp
pid_tools.lsp	P&ID specific operations	drafting_helpers.lsp
attribute_tools.lsp	Block attribute handling	pid_tools.lsp
advanced_geometry.lsp	Extended geometry creation	basic_shapes.lsp
advanced_entities.lsp	Complex entity creation	advanced_geometry.lsp
annotation_helpers.lsp	Text and dimension tools	basic_shapes.lsp
entity_modification.lsp	Entity manipulation	drafting_helpers.lsp

⚡ Performance Optimization

Fast Mode Benefits

• 80% faster drawing operations using batch tools
• 90% faster server initialization with essential files only
• Clipboard-based script execution for complex operations

Batch Operation Examples

# Instead of 10 separate create_line calls (8 seconds)
batch_create_lines([
    [0, 0, 100, 0],
    [100, 0, 100, 100],
    [100, 100, 0, 100],
    # ... more lines
])  # Single call (0.8 seconds)

Performance Settings

Adjust performance based on your system:

# Fast systems
set_performance_mode(fast_mode=True, minimal_delay=0.03)

# Slower systems (more reliable)
set_performance_mode(fast_mode=False, minimal_delay=0.1)

🔍 Troubleshooting

Common issues and solutions:

LISP Loading Issues

• Problem: "LOAD failed" errors
• Solution: Add LISP directory to AutoCAD trusted paths
• See: TROUBLESHOOTING.md

CTO Library Issues

• Problem: "File not found" for P&ID symbols
• Solution: Verify CTO installation path or use standard server
• Alternative: Use server_lisp.py without P&ID functionality

Window Focus Problems

• Problem: Commands not reaching AutoCAD
• Solution: Ensure AutoCAD is active, run as Administrator
• See: TROUBLESHOOTING.md

📊 What's New in This Version

Version 2.0 Features

• ✅ Complete CTO Library Integration (600+ P&ID symbols)
• ✅ Intelligent Block Attributes for equipment schedules
• ✅ Fast Mode Server with 80% performance improvement
• ✅ Batch Operations for multiple object creation
• ✅ Process Engineering Tools for P&ID creation
• ✅ Industry Standard Layers for professional drawings
• ✅ Enhanced Error Handling and troubleshooting guides

Migration from v1.0

Users of the original version should:

1. Update to server_lisp_fast.py for better performance
2. Add CTO library path if available
3. Review new P&ID tools for process drawings
4. Update Claude Desktop configuration

📄 License

MIT License - See LICENSE file for details

🤝 Contributing

Contributions are welcome! Please:

1. Fork the repository
2. Create a feature branch
3. Test with both CTO and non-CTO configurations
4. Submit a pull request with clear documentation

📞 Support

• Issues: GitHub Issues
• Documentation: TROUBLESHOOTING.md
• Performance: PERFORMANCE_OPTIMIZATION.md

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For detailed troubleshooting and advanced configuration, see the additional documentation files in this repository.