Hroerkr/mssqlmcp

SQL Server MCP (Model Context Protocol) Server

A .NET 8 implementation of an MCP server that provides SQL Server database access to MCP-compatible AI assistants like Claude Code.

Features

• Execute SQL queries (SELECT, INSERT, UPDATE, DELETE, etc.)
• Get SQL Server instance and database information
• List tables and their schemas
• Retrieve column information for specific tables
• Supports both Windows Authentication and SQL Server Authentication
• Built on .NET 8 with modern async/await patterns

Prerequisites

• .NET 8.0 SDK
• SQL Server instance (local or remote)
• An MCP-compatible client (like Claude Code)

Installation

1. Clone the repository:

   git clone <your-repo-url>
   cd SqlServerMCP
   

2. Build the project:

   dotnet build
   

3. Test the build:

   # Use the provided test scripts
   build.bat           # Basic build with package check
   full_test.bat       # Complete build and runtime test
   test_direct.bat     # Direct MCP server test
   

Configuration

Environment Variables

Configure your SQL Server connection using these environment variables:

• MSSQL_SERVER: SQL Server instance (default: localhost)
• MSSQL_DATABASE: Database name (default: master)
• MSSQL_USER: SQL Server username (optional - uses Windows Auth if not provided)
• MSSQL_PASSWORD: SQL Server password (optional - uses Windows Auth if not provided)

Example Configuration

Windows Authentication:

set MSSQL_SERVER=localhost
set MSSQL_DATABASE=MyDatabase

SQL Server Authentication:

set MSSQL_SERVER=localhost
set MSSQL_DATABASE=MyDatabase
set MSSQL_USER=sa
set MSSQL_PASSWORD=YourPassword

Claude Code Integration

To use this MCP server with Claude Code, add the following configuration to your ~/.claude.json file:

{
  "projects": {
    "your-project-path": {
      "mcpServers": {
        "sqlserver": {
          "command": "dotnet",
          "args": [
            "run",
            "--project",
            "/path/to/SqlServerMCP/SqlServerMCP.csproj",
            "--no-build"
          ],
          "env": {
            "MSSQL_SERVER": "localhost",
            "MSSQL_DATABASE": "YourDatabase",
            "MSSQL_USER": "sa",
            "MSSQL_PASSWORD": "YourPassword"
          }
        }
      }
    }
  }
}

Note: Replace /path/to/SqlServerMCP/SqlServerMCP.csproj with the actual path to your project file.

Available MCP Tools

Once connected, the following tools will be available to your AI assistant:

ExecuteSql

Execute any SQL query (SELECT, INSERT, UPDATE, DELETE, etc.)

• Parameter: query - The SQL query to execute
• Returns: Query results for SELECT queries or execution status for modification queries

GetServerInfo

Get information about the SQL Server instance and current database

• Returns: Server version, current database, current user, server name, and current date/time

ListTables

List all tables in the current database

• Returns: Table schema names, table names, and table types

GetTableSchema

Get column information for a specific table

• Parameter: tableName - The name of the table to inspect
• Returns: Column details including name, data type, nullability, default values, and constraints

Usage Examples

After setting up the MCP server with Claude Code, you can use natural language commands like:

• "Show me all tables in the database"
• "What's the schema for the Users table?"
• "Execute this query: SELECT * FROM Products WHERE Price > 100"
• "Get information about this SQL Server instance"

Development

Project Structure

• Program.cs: Entry point and MCP server setup
• SqlServerService.cs: Core SQL Server connection and query execution logic
• SqlServerTools.cs: MCP tool definitions and implementations
• SqlServerMCP.csproj: Project configuration and dependencies

Building and Testing

# Clean and build
dotnet clean
dotnet build

# Run the MCP server directly
dotnet run

# Test with provided batch files
full_test.bat

Dependencies

• ModelContextProtocol (0.2.0-preview.1): MCP server framework
• Microsoft.Extensions.Hosting (8.0.1): Dependency injection and hosting
• Microsoft.Extensions.Logging.Console (8.0.1): Logging support
• Microsoft.Data.SqlClient (5.2.2): SQL Server connectivity

Security Considerations

• Connection strings are built dynamically from environment variables
• TrustServerCertificate=true is enabled for development scenarios
• Sensitive information should be stored in environment variables, not hardcoded
• Consider using more secure authentication methods in production environments

Troubleshooting

1. Connection Issues: Verify SQL Server is running and accessible
2. Authentication Failures: Check username/password or Windows Authentication setup
3. Port Issues: Ensure SQL Server is listening on the expected port (default 1433)
4. Firewall: Verify firewall allows connections to SQL Server

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Test thoroughly
5. Submit a pull request

License

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