Microsoft SQL Server MCP Server

When setting up the server, follow these security guidelines:

• Principle of Least Privilege: Create a dedicated SQL user with only the minimum permissions required for your tasks.
• Avoid Admin Accounts: Never use sa or other administrative accounts.
• Prefer Windows Auth: Use Windows Authentication whenever possible.
• Encryption: Enable encryption for all sensitive data connections.

To install the server in editable mode for development purposes, clone the repository and use pip install -e .:

git clone https://github.com/RichardHan/mssql_mcp_server.git
cd mssql_mcp_server
pip install -e .

If you prefer using pip instead of uvx, install the package directly:

pip install microsoft_sql_server_mcp

Then, update your claude_desktop_config.json to use the python -m execution pattern:

{
  "mcpServers": {
    "mssql": {
      "command": "python",
      "args": ["-m", "mssql_mcp_server"],
      "env": { ... }
    }
  }
}

To use the Microsoft SQL Server MCP server with Claude Desktop, add the following configuration to your claude_desktop_config.json file. This method uses uvx to run the server without manual installation.

Ensure you provide the required environment variables for your specific database connection (see Configuration for details).

{
  "mcpServers": {
    "mssql": {
      "command": "uvx",
      "args": ["microsoft_sql_server_mcp"],
      "env": {
        "MSSQL_SERVER": "localhost",
        "MSSQL_DATABASE": "your_database",
        "MSSQL_USER": "your_username",
        "MSSQL_PASSWORD": "your_password"
      }
    }
  }
}

The mcp_server service in the docker-compose.yml connects to the SQL Server instance using the following environment variables:

• MSSQL_SERVER: The hostname or IP of the SQL Server. Defaults to mssql.
• MSSQL_PORT: The port the SQL Server is listening on. Defaults to 1433.
• MSSQL_USER: The database user. Defaults to sa.
• MSSQL_PASSWORD: The password for the database user. Defaults to StrongPassword123!.
• MSSQL_DATABASE: The default database to connect to. Defaults to master.

Note: The mcp_server service has a dependency on the mssql service and will only start once the SQL Server healthcheck passes.

# Example environment variables for MCP Server
MSSQL_SERVER=mssql
MSSQL_PORT=1433
MSSQL_USER=sa
MSSQL_PASSWORD=YourSecurePassword
MSSQL_DATABASE=my_db

When running the SQL Server instance using the provided docker-compose.yml, you can customize the database instance using the following environment variables:

• MSSQL_PASSWORD: Sets the sa password. Defaults to StrongPassword123! if not provided.
• HOST_SQL_PORT: Sets the port on your host machine to map to the SQL Server port (1433). Defaults to 1434.
• SQL_MEMORY_LIMIT: Sets the memory limit for the SQL Server container. Defaults to 2g.

The SQL Server instance uses a persistent volume named mssql_data mapped to /var/opt/mssql to ensure data persistence.

# Example environment variables for SQL Server
MSSQL_PASSWORD=YourSecurePassword
HOST_SQL_PORT=1433
SQL_MEMORY_LIMIT=4g

The server provides a tool to execute arbitrary SQL queries against the connected database. By default, the tool name is execute_sql, but this can be customized via the MSSQL_COMMAND environment variable.

Tool Definition

• Name: execute_sql (or your custom MSSQL_COMMAND value)
• Arguments:
  • query (string, required): The full SQL query to execute.

Behavior

• SELECT queries: Returns the results as a CSV-formatted string (columns followed by rows).
• Information Schema queries: If querying INFORMATION_SCHEMA.TABLES, it returns a list of table names.
• Non-SELECT queries (e.g., INSERT, UPDATE, DELETE): Executes the command, commits the transaction, and returns the number of affected rows.

{
  "name": "execute_sql",
  "arguments": {
    "query": "SELECT * FROM users WHERE id = 1"
  }
}

The main() function serves as the primary entry point for the microsoft_sql_server_mcp package. It initializes and runs the MCP server using an asynchronous event loop. This is useful if you are integrating the server into a custom Python script or running it as a module.

from mssql_mcp_server import main

if __name__ == "__main__":
    main()

The server exposes database tables as MCP resources, allowing you to inspect table data using a standardized URI scheme.

Resource URI Format

mssql://<table_name>/data

Reading Data

When you read a resource URI, the server executes a SELECT TOP 100 * FROM <table_name> query and returns the data as a CSV-formatted string.

Note: Table names are validated to prevent SQL injection. Only alphanumeric characters, underscores, and dots (for schema.table notation) are allowed.

mssql://my_table/data