BESSER-MCP-Server

BESSER-PEARL/BESSER-MCP-Server

3.3

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A minimal Model Context Protocol (MCP) server implementation for BESSER, the Python-based low-code modeling platform.

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BESSER-MCP-Server

A minimal Model Context Protocol (MCP) server implementation for BESSER, the Python-based low-code modeling platform.

Overview

This MCP server provides access to BESSER's low-code platform modeling and code generation capabilities through the Model Context Protocol, enabling AI assistants and other MCP clients to interact with BESSER's features.

Features

The BESSER MCP Server can be used both locally or deployed on a server. To deploy it, the --dist or -d option needs to be added when starting the server Both the local and distant implementation open the server on the following address: http://127.0.0.1:8000/sse. However, the port can be changed through the --port or -p option. Help on the server option can be printed using the --help or -h option.

The BESSER MCP Server provides the following tools:

  • Information tools:
    • about: Get information about BESSER and this MCP server
    • get_model_info: Get detailed information about an existing domain model (classes, attributes, methods, relationships)
  • Creation tools:
    • new_model: Create a new B-UML DomainModel with a specified name
    • add_class: Add a new class in the model
    • add_method_to_class: Add a method to a given class
    • add_attribute_to_class: Add an attribute to a given class
    • add_binary_association: Add a binary association between two classes
    • add_association_class: Add an association class to an existing association
    • add_enumeration: Add an enumeration to the model
    • add_enumeration_literal: Add a literal to an enumeration
    • add_generalization: Add a generalization relation between two classes
    • add_ocl_constraint: Add an OCL constraint to a class
  • Deletion tools:
    • delete_class: Remove a class from the model
    • delete_method_to_class: Remove a method from a given class
    • delete_attribute_to_class: Remove an attribute from a given class
    • delete_binary_association: Remove a binary association between two classes
    • delete_association_class: Remove an association class from an existing association
    • delete_enumeration: Remove an enumeration from the model
    • delete_enumeration_literal: Remove a literal from an enumeration
    • delete_generalization: Remove a generalization relation between two classes
    • delete_ocl_constraint: Remove an OCL constraint
  • Generation tools:
    • sql_generation: Generate the SQL representation of the model
    • python_generation: Generate the set of Python classes implementing the model
    • backend_generation: Generate a backend implementation for the model
    • java_generation: Generate the set of Java classes implementing the model
    • json_schema_generation: Generate the JSON Schema of the model
    • json_smart_data_generation: Generate the Smart Data Schema for the model
    • pydantic_classes_generation: Generate a Pydentic representation of the model
    • rdf_generation: Generate the RDF vocabulary for the model
    • rest_api_generation: Generate a Rest API for the model
    • sql_alchemy_generation: Generate the SQLAlchemy code for the model

If the server is started locally, the server will directly access the file system for file generation. If the server is distant, the generated code will be sent back to the LLM. For this reason, generators producing multiple files are currently disabled in the distant mode.

Prerequisites

Before using the MCP server, ensure you have:

  • Python 3.8+ installed
  • Required packages: 
    pip install mcp besser
    Or if using UV: 
    uv add mcp besser

Usage

Running the Server

Production Mode

Run the MCP server directly:

python src/besser_mcp_server/server.py

Or install the package and run it:

pip install -e .
python -m besser_mcp_server.server
Development Mode

For development and debugging, use the MCP development server which includes the MCP inspector:

mcp dev src/besser_mcp_server/server.py

This will:

  • Start the server in development mode
  • Launch the MCP inspector in your browser for interactive testing
  • Provide detailed logging and debugging information
  • Allow you to test tools directly without configuring a client

Configuring MCP Clients

To use this server with MCP clients like Claude Desktop, Cursor and Cline, you need to configure them to connect to the server.

Recommended setup (Cline)
  1. Open the Cline panel on VScode
  2. Click on "Manage MCP Server" at the bottom, then the cog
  3. Clicking on "Configure MCP server" will open the configuration file
  4. Add the "besser-mcp-server" in the "mcpServers" section: 
    {
  "mcpServers": {
    "besser-mcp": {
      "url": "http://127.0.0.1:8000/sse"
    }
  }
}
Quick Setup (Windows)

Use the provided PowerShell installation script:

# For Cursor IDE
.\install-mcp-config.ps1 -Client cursor

# For Claude Desktop
.\install-mcp-config.ps1 -Client claude

# For both clients
.\install-mcp-config.ps1 -Client both
Manual Configuration
Cline
  1. Open the Cline panel on VScode
  2. Click on "Manage MCP Server" at the bottom, then the cog
  3. Clicking on "Configure MCP server" will open the configuration file
  4. Add the "besser-mcp-server" in the "mcpServers" section: 
    {
  "mcpServers": {
    "besser-mcp": {
      "url": "http://127.0.0.1:8000/sse"
    }
  }
}
Claude Desktop

  1. Locate the configuration directory:

    • macOS: ~/Library/Application Support/Claude/
    • Windows: %APPDATA%\Claude\

  2. Create or edit claude_desktop_config.json:

    {
  "mcpServers": {
    "besser-mcp": {
      "type": "sse",
      "url": "http://127.0.0.1:8000/sse"
    }
  }
}
Cursor IDE

  1. Create the Cursor MCP configuration directory:

    mkdir -p ~/.cursor  # macOS/Linux
# or
mkdir %USERPROFILE%\.cursor  # Windows

  2. Create or edit ~/.cursor/mcp.json:

    {
  "mcpServers": {
    "besser-mcp": {
      "url": "http://127.0.0.1:8000/sse"
    }
  }
}

Distant mode for collaboration

By using and sharing a URL where the model can be saved multiple users can edit the same model. To do so, you have to deploy the MCP server on distant mode using the -d or --dist option. You can change the port used for this server using the -p or --port option followed by the port number.

With this server, users can change the model by giving the URL as parameter. Example prompt:

Add a class representing users in the model available at the URL https://my-domain.com/model

Disclaimer: the distant mode currently has limitations regarding concurrent access and multi-file generation

Testing the Connection

After configuring your MCP client:

  1. Start the server
  2. Restart your MCP client
  3. Test the connection by asking:
    • "What is BESSER?" (uses the about tool)
    • "Create a new domain model called 'MyModel'" (uses new_model)
    • "Add a class named 'Person' to the model" (uses add_class)
    • "Show me information about the domain model" (uses get_model_info)
    • "Generate SQL from the domain model" (uses sql_generation)

Configuration Files

The repository includes several pre-configured files to help with setup:

  • mcp-config.json - Basic cross-platform configuration template
  • mcp-config-examples.json - Multiple configuration examples
  • claude-desktop-config-windows.json - Windows-specific Claude Desktop config
  • cursor-mcp-config-windows.json - Windows-specific Cursor config
  • install-mcp-config.ps1 - Automatic installation script for Windows

Documentation

For detailed setup instructions and troubleshooting:

  • QUICK-START.md - Fast setup guide
  • MCP-CLIENT-SETUP.md - Comprehensive setup instructions with troubleshooting

Example Usage

Once connected, you can interact with BESSER through natural language:

User: "Create a new domain model called 'ECommerceSystem'"
Assistant: [Uses new_model tool to create the model]

User: "Add a Customer class to the ECommerceSystem model"  
Assistant: [Uses add_class tool to add the Customer class]

User: "Add a Product class as well"
Assistant: [Uses add_class tool to add the Product class]

User: "Show me information about the current domain model"
Assistant: [Uses get_model_info tool to display model structure, classes, and relationships]

User: "Generate SQL from this domain model"
Assistant: [Uses sql_generation tool to create SQL representation]

User: "What is BESSER?"
Assistant: [Uses about tool to provide information about BESSER]

Troubleshooting

Common Issues

  1. "mcp is not found" or import errors:

    • Make sure you have the correct MCP package installed: pip install mcp
    • If you have an older version, upgrade it: pip install --upgrade mcp
    • Verify installation: python -c "import mcp.server; print('MCP installed correctly')"

  2. "Command not found" errors: Ensure Python is in your system PATH

  3. "Permission denied" errors: Ensure the server script has appropriate permissions

License

This project is licensed under the MIT License - see the file for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.