mcp-sqlserver

MCP server for Microsoft SQL Server with explicit port support. Works from Claude Code, Cursor, and CLI; default port is 9123 (override with MSSQL_PORT).

Why this exists

Generic mssql-mcp-server packages can fail when run from Claude Code with a custom port: connection works from the CLI but not when the client spawns the process. This server reads config from environment variables and passes port as a number into the driver so behavior is consistent everywhere.

Requirements

• Node.js 18+

• SQL Server reachable via TCP (default port 9123, or set MSSQL_PORT)

• For Windows Integrated Auth (current user, no password): npm install msnodesqlv8 (Windows native driver)

Setup

cd mcp-sqlserver
npm install
npm run build

Configuration

Option A: Connections map file (per environment / client)

Use a JSON file so each MCP server block only sets environment and client (and optionally the file path). One server (e.g. 192.168.100.65) can host multiple databases; each is a client with its own database name and credentials. You run one MCP server block per database (same server, different MSSQL_CLIENT).

File structure (e.g. connections.json): environment -> { server, port, encrypt?, trustServerCertificate?, windowsIntegrated?, clients: { clientName -> { database, user?, password?, domain?, windowsIntegrated? } } }. Server settings are shared; each client has database and either SQL credentials (user/password), NTLM (domain + user/password), or Windows Integrated (windowsIntegrated: true, no user/password).

If both MSSQL_ENVIRONMENT and MSSQL_CLIENT are set, the server loads the file, uses the environment’s server/port/encrypt/trustServerCertificate, and the client’s database and auth. Any of MSSQL_SERVER, MSSQL_PORT, MSSQL_DATABASE, MSSQL_USER, MSSQL_PASSWORD, MSSQL_DOMAIN, MSSQL_ENCRYPT, MSSQL_TRUST_CERT, MSSQL_WINDOWS_INTEGRATED in env override the file values.

Windows authentication

• NTLM (domain user)
  In the client entry set domain with user and password (e.g. domain: "MYDOMAIN" for MYDOMAIN\myuser). Uses the default driver (tedious). Env override: MSSQL_DOMAIN.

• Windows Integrated (current OS user)
  In the client entry set windowsIntegrated: true; omit user and password. Uses the msnodesqlv8 driver (Windows native). Install it with npm install msnodesqlv8. You can set windowsIntegrated: true at the environment level to apply to all clients, or per client. Env override: MSSQL_WINDOWS_INTEGRATED=true.

Example connections.example.json (copy to connections.json and fill in real values):

{
  "staging": {
    "server": "192.168.100.65",
    "port": 9123,
    "encrypt": true,
    "trustServerCertificate": true,
    "clients": {
      "QASandbox8": {
        "database": "QASandbox8",
        "user": "usrQASandbox8",
        "password": "your-password"
      },
      "OtherDatabase": {
        "database": "OtherDatabase",
        "user": "usrOtherDb",
        "password": "your-password"
      },
      "NTLM_Database": {
        "database": "MyDb",
        "domain": "MYDOMAIN",
        "user": "myuser",
        "password": "my-password"
      },
      "WindowsIntegratedDb": {
        "database": "TrustedDb",
        "windowsIntegrated": true
      }
    }
  }
}

Example MCP blocks: one per database on the same server (same staging server, different MSSQL_CLIENT):

"mssql-staging-qa": {
  "command": "node",
  "args": ["C:\\Code\\AI-Examples\\mcp\\mcp-sqlserver\\dist\\index.js"],
  "env": {
    "MSSQL_ENVIRONMENT": "staging",
    "MSSQL_CLIENT": "QASandbox8",
    "MSSQL_CONFIG_PATH": "C:\\Code\\AI-Examples\\mcp\\mcp-sqlserver\\connections.json"
  }
},
"mssql-staging-other": {
  "command": "node",
  "args": ["C:\\Code\\AI-Examples\\mcp\\mcp-sqlserver\\dist\\index.js"],
  "env": {
    "MSSQL_ENVIRONMENT": "staging",
    "MSSQL_CLIENT": "OtherDatabase",
    "MSSQL_CONFIG_PATH": "C:\\Code\\AI-Examples\\mcp\\mcp-sqlserver\\connections.json"
  }
}

Option B: Environment variables only

* Omit when using Windows Integrated auth (MSSQL_WINDOWS_INTEGRATED=true).

Claude Code / Cursor

Add your MCP server block under mcpServers in Claude Code or Cursor (e.g. Settings → MCP). Use one of these:

• With a connections file (Option A) – Put connections.json next to the project (or set MSSQL_CONFIG_PATH). In the MCP config you only set environment, client, and path:

"mssql-staging-qa": {
  "command": "node",
  "args": ["C:\\Code\\AI-Examples\\mcp\\mcp-sqlserver\\dist\\index.js"],
  "env": {
    "MSSQL_ENVIRONMENT": "staging",
    "MSSQL_CLIENT": "QASandbox8",
    "MSSQL_CONFIG_PATH": "C:\\Code\\AI-Examples\\mcp\\mcp-sqlserver\\connections.json"
  }
}

• Without a file (Option B) – Pass everything via env (server, port, database, user, password, etc.):

"mssql": {
  "command": "node",
  "args": ["C:\\Code\\AI-Examples\\mcp\\mcp-sqlserver\\dist\\index.js"],
  "env": {
    "MSSQL_SERVER": "192.168.100.65",
    "MSSQL_PORT": "9123",
    "MSSQL_DATABASE": "QASandbox8",
    "MSSQL_USER": "usrQASandbox8",
    "MSSQL_PASSWORD": "your-password",
    "MSSQL_ENCRYPT": "true",
    "MSSQL_TRUST_CERT": "true"
  }
}

Replace args[0] with the absolute path to dist/index.js on your machine.

Tools

• query – Run a read-only SQL query (e.g. SELECT ...). Returns results as a text table.

• list_tables – List tables in the current database. Optional schema argument (e.g. dbo).

• describe_table – Column names and types for a table. Arguments: table, optional schema (default dbo).

Run locally (stdio)

# Set env vars, then:
npm run start
# or without building:
npm run dev

The server speaks MCP over stdio; a client (Claude Code, Cursor, or another MCP client) must start it and connect to stdin/stdout.

License

MIT