SQL Server MCP Server

A Model Context Protocol (MCP) server that provides tools for interacting with SQL Server databases. This server allows Large Language Models (LLMs) to query and inspect SQL Server databases through a standardized protocol.

Features

• Database Querying: Execute SQL queries and retrieve results
• Schema Inspection: List tables, views, stored procedures, and examine table schemas
• SQL Injection Prevention: Built-in validation to prevent SQL injection attacks
• Resource Caching: Metadata caching for improved performance

Getting Started

Prerequisites

• .NET 10.0 SDK or later (or Docker)
• SQL Server instance (local or remote)

Installation

Option 1: Docker (Recommended)

Run the server using Docker without installing .NET:

# Build the image
docker build -t tsql-mcp-server .

# Run with connection string
docker run -i tsql-mcp-server --dsn "Server=host.docker.internal;Database=mydb;User Id=sa;Password=mypassword;TrustServerCertificate=True;"

# Run in read-only mode
docker run -i tsql-mcp-server --dsn "..." --read-only

# Run with environment variable
docker run -i -e SQL_CONNECTION="Server=..." tsql-mcp-server --env-var SQL_CONNECTION

Notes:

• The -i flag is required for stdio transport
• Use host.docker.internal to connect to SQL Server on your host machine
• For WSL2 users: if host.docker.internal doesn't resolve, use --network host and localhost instead

Option 2: Install as a .NET Tool

Install globally as a .NET tool:

dotnet tool install --global tsql-mcp-server

To update to the latest version:

dotnet tool update --global tsql-mcp-server

Option 2: Build from Source

# Clone the repository
git clone https://github.com/Popplywop/tsql-mcp-server
cd tsql-mcp-server

# Build the project
dotnet build

Running the Server

Using the .NET Tool

If installed as a .NET global tool:

# Using a direct connection string
tsql-mcp-server --dsn "Server=your-server;Database=your-database;User Id=your-username;Password=your-password;TrustServerCertificate=True;"

# Using an environment variable
tsql-mcp-server --env-var "SQL_CONNECTION_STRING"

Using Source Code

If building from source:

# Using a direct connection string
dotnet run --dsn "Server=your-server;Database=your-database;User Id=your-username;Password=your-password;TrustServerCertificate=True;"

# Using an environment variable
dotnet run --env-var "SQL_CONNECTION_STRING"

MCP Server Configuration

To use this server with Claude or other LLMs that support the Model Context Protocol, you'll need to configure it in your MCP configuration file.

If Installed as a .NET Tool

{
  "servers": [
    {
      "name": "SqlServerMcp",
      "command": "tsql-mcp-server",
      "args": [
        "--dsn",
        "Server=your-server;Database=your-database;User Id=your-username;Password=your-password;TrustServerCertificate=True;"
      ]
    }
  ]
}

If Built from Source

{
  "servers": [
    {
      "name": "SqlServerMcp",
      "command": "path/to/tsql-mcp-server.exe",
      "args": [
        "--dsn",
        "Server=your-server;Database=your-database;User Id=your-username;Password=your-password;TrustServerCertificate=True;"
      ]
    }
  ]
}

Replace the connection string with your actual values. This configuration can be used with Claude's MCP integration or other LLM platforms that support the Model Context Protocol.

Using Docker

{
  "mcpServers": {
    "sqlserver": {
      "command": "docker",
      "args": [
        "run", "-i", "--rm", "tsql-mcp-server",
        "--dsn", "Server=host.docker.internal;Database=your-database;User Id=your-username;Password=your-password;TrustServerCertificate=True;"
      ]
    }
  }
}

For read-only mode, add "--read-only" to the args array.

Using Environment Variables for Sensitive Information

For better security, you can use environment variables for your connection string:

{
  "servers": [
    {
      "name": "SqlServerMcp",
      "command": "tsql-mcp-server",
      "args": [
        "--env-var",
        "SQL_CONNECTION_STRING"
      ]
    }
  ]
}

Command Line Options

Available MCP Tools

Query Tools

• ExecuteQuery: Executes a SQL query against the database and returns the results

  • Parameters:
    • query: The SQL query to execute
    • commandTimeout: Optional command timeout in seconds
    • maxRows: Optional maximum number of rows to return

• ExecuteStoredProcedure: Executes a stored procedure with optional parameters

  • Parameters:
    • schema: The schema name (e.g., 'dbo')
    • procedureName: The stored procedure name
    • parametersJson: Optional JSON object of parameters (e.g., {"@param1": "value"})
    • commandTimeout: Optional command timeout in seconds
    • maxRows: Optional maximum number of rows to return

Schema Tools (Token-Optimized)

Lightweight tools for exploring database structure without fetching data:

• GetTableColumns: Get column names and types for a table
• GetTableRowCount: Get row count for a table
• ListTables: List all tables in a schema (with optional row counts)
• GetPrimaryKey: Get primary key columns for a table
• GetSampleData: Get a small sample of data (max 20 rows)

Database Resources

The server provides database schema information through a resource-based approach. Resources are accessed via URIs and are lazy-loaded with caching for improved performance.

Note: View and procedure definitions are excluded by default to reduce token usage. Use the /definition endpoint when you need the SQL source code.

Resources are automatically discovered by the MCP client and can be accessed directly without requiring specific tool calls.

Security Considerations

• Use a SQL Server account with appropriate permissions (principle of least privilege)
• Store connection strings securely (not in source control)
• Consider using environment variables for connection strings
• Enable TLS/SSL for database connections
• SQL injection validation prevents dangerous operations and protects against common attack vectors

Example Usage

Querying Data

ExecuteQuery:
  query: "SELECT TOP 10 * FROM MyTable"
  maxRows: 100

Accessing Database Resources

Resources can be accessed directly via their URIs:

# List all schemas
GET sqlserver://schemas

# Get information about a specific schema
GET sqlserver://schemas/dbo

# List all tables in a schema
GET sqlserver://schemas/dbo/tables

# Get detailed information about a specific table
GET sqlserver://schemas/dbo/tables/Customers

The resource-based approach provides a RESTful way to explore and interact with the database schema.

License

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

The MIT License is a permissive license that allows for reuse with minimal restrictions. It permits anyone to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the software, subject to the condition that the original copyright notice and permission notice appear in all copies.