mssql-mcp

MCP server for Microsoft SQL Server. Supports Windows Authentication and SQL Server Authentication via the native msnodesqlv8 ODBC driver.

Requirements

• Windows (native ODBC driver required)

• ODBC Driver 17 or 18 for SQL Server

• Node.js >= 18

The ODBC driver is auto-detected from the Windows registry — no configuration needed.

Installation

npm install
npm run build

Configuration

All configuration is via environment variables. No .env file is required when running via an MCP host — set env in the MCP config instead.

Authentication

Windows Authentication (use the current Windows user — no credentials needed):

MSSQL_SERVER=myserver

SQL Server Authentication (provide both user and password):

MSSQL_SERVER=myserver
MSSQL_USER=sa
MSSQL_PASSWORD=secret

Note: MSSQL_USER and MSSQL_PASSWORD must both be set or both be absent. Setting only one will throw an error.

Multiple servers

Use MSSQL_<KEY>_SERVER to configure multiple servers. Each key becomes a selectable dbKey in the MCP tools.

Windows auth on all servers:

MSSQL_PROD_SERVER=prod-server
MSSQL_QA_SERVER=qa-server
MSSQL_DEV_SERVER=dev-server

Mixed auth:

MSSQL_PROD_SERVER=prod-server

MSSQL_DEV_SERVER=dev-server
MSSQL_DEV_USER=sa
MSSQL_DEV_PASSWORD=secret

Each key can also override the ODBC driver:

MSSQL_PROD_DRIVER=ODBC Driver 18 for SQL Server

Or set a global override for all servers:

MSSQL_DRIVER=ODBC Driver 17 for SQL Server

Optional: port

MSSQL_PORT=1433
# or per-key: MSSQL_PROD_PORT=1433

MCP Host Config

Claude Desktop (claude_desktop_config.json)

Single server — Windows auth:

{
  "mcpServers": {
    "mssql": {
      "command": "node",
      "args": ["/path/to/mssql-mcp/dist/index.js"],
      "env": {
        "MSSQL_SERVER": "your-server"
      }
    }
  }
}

Single server — SQL auth:

{
  "mcpServers": {
    "mssql": {
      "command": "node",
      "args": ["/path/to/mssql-mcp/dist/index.js"],
      "env": {
        "MSSQL_SERVER": "your-server",
        "MSSQL_USER": "sa",
        "MSSQL_PASSWORD": "secret"
      }
    }
  }
}

Multiple servers:

{
  "mcpServers": {
    "mssql": {
      "command": "node",
      "args": ["/path/to/mssql-mcp/dist/index.js"],
      "env": {
        "MSSQL_PROD_SERVER": "prod-server",
        "MSSQL_QA_SERVER": "qa-server",
        "MSSQL_DEV_SERVER": "dev-server",
        "MSSQL_DEV_USER": "sa",
        "MSSQL_DEV_PASSWORD": "secret"
      }
    }
  }
}

VS Code (mcp.json)

{
  "servers": {
    "mssql": {
      "type": "stdio",
      "command": "node",
      "args": ["/path/to/mssql-mcp/dist/index.js"],
      "env": {
        "MSSQL_SERVER": "your-server"
      }
    }
  }
}

Tools

When multiple servers are configured, each tool accepts a dbKey parameter to select the target server.

Notes

• The LLM should use fully-qualified table names (e.g. MyDatabase.dbo.Orders) — no database selection is needed in config.

• Connection pools are created lazily on first use and reused across calls.