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:

Install the CTO library to C:\PIDv4-CTO\
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

Launch AutoCAD LT
- Create or open a drawing
- Ensure command line is visible
Start the Server
# For users with CTO library (recommended) start_fast_server.bat # For users without CTO library start_lisp_server.bat
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:

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

📄 License

MIT License - See LICENSE file for details

🤝 Contributing

Contributions are welcome! Please:

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

📞 Support

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

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

This server cannot be installed

security - not tested

license - permissive license

quality - not tested

local-only server

The server can only run on the client's local machine because it depends on local resources.

Enables natural language control of AutoCAD LT through AutoLISP code generation and execution, allowing users to create engineering drawings with conversational prompts.

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