MS SQL MCP Server

An easy-to-use bridge that lets AI assistants like Claude directly query and explore Microsoft SQL Server databases. No coding experience required!

What Does This Tool Do?

This tool allows AI assistants to:

Discover tables in your SQL Server database
View table structures (columns, data types, etc.)
Execute read-only SQL queries safely
Generate SQL queries from natural language requests

🚀 Quick Start Guide

Step 1: Install Prerequisites

Install Node.js (version 14 or higher)
Have access to a Microsoft SQL Server database (on-premises or Azure)

Step 2: Clone and Setup

# Clone this repository
git clone https://github.com/dperussina/mssql-mcp-server.git

# Navigate to the project directory
cd mssql-mcp-server

# Install dependencies
npm install

# Copy the example environment file
cp .env.example .env

Step 3: Configure Your Database Connection

Edit the .env file with your database credentials:

DB_USER=your_username
DB_PASSWORD=your_password
DB_SERVER=your_server_name_or_ip
DB_DATABASE=your_database_name
PORT=3333
TRANSPORT=stdio
SERVER_URL=http://localhost:3333
DEBUG=false                     # Set to 'true' for detailed logging (helpful for troubleshooting)
QUERY_RESULTS_PATH=/path/to/query_results  # Directory where query results will be saved as JSON files

Step 4: Start the Server

# Start with default stdio transport
npm start

# OR start with HTTP/SSE transport for network access
npm run start:sse

Step 5: Try it out!

# Run the interactive client
npm run client

📊 Example Use Cases

Explore your database structure without writing SQL
mcp__discover_database()
Get detailed information about a specific table
mcp__table_details({ tableName: "Customers" })
Run a safe query
mcp__execute_query({ sql: "SELECT TOP 10 * FROM Customers" })
Ask natural language questions
"Show me the top 5 customers with the most orders in the last month"

🔄 Transport Methods Explained

Option 1: stdio Transport (Default)

Best for: Using directly with Claude Desktop or the bundled client

npm start

Option 2: HTTP/SSE Transport

Best for: Network access or when used with web applications

npm run start:sse

🖥️ Interactive Client Features

The bundled client provides an easy menu-driven interface:

List available resources - See what information is available
List available tools - See what actions you can perform
Execute SQL query - Run a read-only SQL query
Get table details - View structure of any table
Read database schema - See all tables and their relationships
Generate SQL query - Convert natural language to SQL

🔗 Claude Desktop Integration

Connect this tool directly to Claude Desktop in a few easy steps:

Install Claude Desktop from anthropic.com
Edit Claude's configuration file:
- Location: ~/Library/Application Support/Claude/claude_desktop_config.json
- Add this configuration:

{
    "mcpServers": {
        "mssql": {
            "command": "node",
            "args": [
                "/FULL/PATH/TO/mssql-mcp-server/server.mjs"
            ]
        }
    }
}

Replace /FULL/PATH/TO/ with the actual path to where you cloned this repository
Restart Claude Desktop
Look for the tools icon in Claude Desktop - you can now use database commands directly!

🔌 Connecting with Cursor IDE

Cursor is an AI-powered code editor that can leverage this tool for advanced database interactions. Here's how to set it up:

Setup in Cursor

Open Cursor IDE (download from cursor.sh if you don't have it)
Start the MS SQL MCP Server using the HTTP/SSE transport:
npm run start:sse
Create a new workspace or open an existing project in Cursor
Enter Cursor Settings
Click MCP
Add new MCP server
Name your MCP server, select type: sse
Enter server URL as: localhost:3333/sse (or the port you have it running on)

Using Database Commands in Cursor

Once connected, you can use MCP commands directly in Cursor's AI chat:

Ask Claude in Cursor to explore your database:
Can you show me the tables in my database?
Execute specific queries:
Query the top 10 records from the Customers table
Generate and run complex queries:
Find all orders from the last month with a value over $1000

Troubleshooting Cursor Connection

Make sure the MS SQL MCP Server is running with the HTTP/SSE transport
Check that the port is correct and matches what's in your .env file
Ensure your firewall isn't blocking the connection
If using a different IP/hostname, update the SERVER_URL in your .env file

🛡️ Security Features

Read-only by default: No risk of data modification
Private credentials: Database connection details stay in your .env file
SQL injection protection: Built-in validation for SQL queries

🔎 Troubleshooting for New Users

"Cannot connect to database"

Check your .env file for correct database credentials
Make sure your SQL Server is running and accepting connections
For Azure SQL, verify your IP is allowed in the firewall settings

"Module not found" errors

Run npm install again to ensure all dependencies are installed
Make sure you're using Node.js version 14 or higher

"Transport error" or "Connection refused"

For HTTP/SSE transport, verify the PORT in your .env is available
Make sure no firewall is blocking the connection

Claude Desktop can't connect

Double-check the path in your claude_desktop_config.json
Ensure you're using absolute paths, not relative ones
Restart Claude Desktop completely after making changes

📚 Understanding SQL Server Basics

If you're new to SQL Server, here are some key concepts:

Tables: Store your data in rows and columns
Schemas: Logical groupings of tables (like folders)
Queries: Commands to retrieve or analyze data
Views: Pre-defined queries saved for easy access

This tool helps you explore all of these without needing to be a SQL expert!

📝 License

ISC

🧠 Guide to Effective AI Prompts for Database Exploration

When working with Claude or other AI assistants through this MCP server, the way you phrase your requests significantly impacts the results. Here's how to help the AI use the database tools effectively:

Essential Commands for AI Database Interaction

The AI can use these MCP commands when prompted properly:

1. Database Discovery

mcp__discover_database()

When to suggest: Start with this when the AI is unfamiliar with your database. Example prompt: "Use the discover database tool to see what tables are available."

2. Table Details

mcp__table_details({ tableName: "YourTableName" })

When to suggest: When focusing on a specific table. Example prompt: "Check the structure of the Orders table before querying it."

3. Query Execution

mcp__execute_query({ 
  sql: "SELECT * FROM YourTable WHERE Condition", 
  returnResults: true 
})

When to suggest: When you want to see query results directly in the conversation. Example prompt: "Run a query to show me the most recent orders, and display the results here."

Effective Prompting Patterns

Start with Structure, Then Query

First, discover what tables exist in my database. Then, look at the structure
of the Customers table. Finally, show me the top 10 customers by total purchase amount.

Guide the AI Through Complex Analysis

I need to analyze our sales data. First, check the structure of the Sales and Products tables.
Then, write a query that shows monthly sales totals by product category for the last quarter.

Ask for Explanations

Query the top 5 underperforming products based on sales vs. forecasts,
and explain your approach to writing this query.

Advanced MCP Features

Viewing Large Result Sets

For large query results, the server saves them as JSON files. The AI will provide a UUID to access these results.

mcp__get_query_results({ uuid: "provided-uuid-here" })

Example prompt: "Use the UUID from the previous query to show me the first 20 rows of that result set."

Generating Complex Queries

Help me create a query that shows customer retention rates by month, comparing
new vs. returning customers as a percentage of total sales.

Combining Multiple Tables

I need to analyze data across multiple tables. First, check the structure of
Orders, OrderDetails, and Products tables. Then create a query that shows
our top-selling products by revenue for each geographical region.

Troubleshooting Through Prompts

If the AI is struggling with a database task, try these approaches:

Be more specific about tables: "Before writing that query, please check if the CustomerOrders table exists and what columns it has."
Break complex tasks into steps: "Let's approach this step by step. First, look at the Products table structure. Then, check the Orders table..."
Ask for intermediate results: "Run a simple query on that table first so we can verify the data format before trying more complex analysis."
Request query explanations: "After writing this query, explain what each part does so I can verify it's doing what I need."

⚙️ Environment Configuration Explained

The .env file controls how the MS SQL MCP Server connects to your database and operates. Here's a detailed explanation of each setting:

# Database Connection Settings
DB_USER=your_username           # SQL Server username
DB_PASSWORD=your_password       # SQL Server password
DB_SERVER=your_server_name      # Server hostname or IP address (example: localhost, 10.0.0.1, myserver.database.windows.net)
DB_DATABASE=your_database_name  # Name of the database to connect to

# Server Configuration
PORT=3333                       # Port for the HTTP/SSE server to listen on
TRANSPORT=stdio                 # Connection method: 'stdio' (for Claude Desktop) or 'sse' (for network connections)
SERVER_URL=http://localhost:3333 # Base URL when using SSE transport (must match your PORT setting)

# Advanced Settings
DEBUG=false                     # Set to 'true' for detailed logging (helpful for troubleshooting)
QUERY_RESULTS_PATH=/path/to/query_results  # Directory where query results will be saved as JSON files

Connection Types Explained

stdio Transport

Use when connecting directly with Claude Desktop
Communication happens through standard input/output streams
Set TRANSPORT=stdio in your .env file
Run with npm start

HTTP/SSE Transport

Use when connecting over a network (like with Cursor IDE)
Uses Server-Sent Events (SSE) for real-time communication
Set TRANSPORT=sse in your .env file
Configure SERVER_URL to match your server address
Run with npm run start:sse

SQL Server Connection Examples

Local SQL Server

DB_USER=sa
DB_PASSWORD=YourStrongPassword
DB_SERVER=localhost
DB_DATABASE=AdventureWorks

Azure SQL Database

DB_USER=azure_admin@myserver
DB_PASSWORD=YourStrongPassword
DB_SERVER=myserver.database.windows.net
DB_DATABASE=AdventureWorks

Query Results Storage

Query results are saved as JSON files in the directory specified by QUERY_RESULTS_PATH. This prevents large result sets from overwhelming the conversation. You can:

Leave this blank to use the default query-results directory in the project
Set a custom path like /Users/username/Documents/query-results
Access saved results using the provided UUID in the tool response