@adriancy/mcp-mssql

MCP server (stdio) for Microsoft SQL Server. Exposes tools so Cursor (or any MCP client) can list tables, describe columns, and run read-biased T-SQL.

Use it in Cursor

1. Open Cursor Settings → MCP (or edit your MCP JSON).
2. Add a server block. Set env to your database (see .env.example).

From npm (after the package is published):

{
  "mcpServers": {
    "mssql": {
      "command": "npx",
      "args": ["-y", "@adriancy/mcp-mssql"],
      "env": {
        "MSSQL_SERVER": "localhost",
        "MSSQL_USER": "your_user",
        "MSSQL_PASSWORD": "your_password",
        "MSSQL_DATABASE": "your_database",
        "MSSQL_TRUST_SERVER_CERTIFICATE": "true"
      }
    }
  }
}

From a local clone (run pnpm install && pnpm build first):

{
  "mcpServers": {
    "mssql": {
      "command": "node",
      "args": ["/absolute/path/to/mssql-mcp/dist/index.js"],
      "env": {
        "MSSQL_SERVER": "localhost",
        "MSSQL_USER": "your_user",
        "MSSQL_PASSWORD": "your_password",
        "MSSQL_DATABASE": "your_database",
        "MSSQL_TRUST_SERVER_CERTIFICATE": "true"
      }
    }
  }
}

Use node for local files. Avoid pnpm as the MCP command — extra output on stdout can break the protocol.

Confirm the install name matches npm: npm view @adriancy/mcp-mssql version.

Environment

All variables are read from the MCP process environment (e.g. Cursor env). Booleans treat 1, true, yes, on (case-insensitive) as true and 0, false, no, off as false. Invalid boolean and integer values fail startup validation.

| Variable | Required | Default | Meaning | |----------|----------|---------|---------| | MSSQL_SERVER | yes | — | Hostname or IP of SQL Server | | MSSQL_USER | yes† | — | Login user (SQL auth, NTLM, Azure AD password); not used for azure-active-directory-access-token or service-principal-only flows | | MSSQL_PASSWORD | yes*† | — | Login password (*may be empty for some setups) | | MSSQL_DATABASE | yes | — | Initial database | | MSSQL_PORT | no | 1433 | TCP port; omit when using MSSQL_INSTANCE_NAME (driver uses instance + SQL Browser) | | MSSQL_ENCRYPT | no | true | TLS encrypt: true, false, or strict (TDS 8.0 / tedious) | | MSSQL_TRUST_SERVER_CERTIFICATE | no | false | Trust self-signed / skip cert validation (dev only) | | MSSQL_TLS_SERVER_NAME | no | — | Hostname for TLS validation when it differs from MSSQL_SERVER (e.g. connect by IP) | | MSSQL_TLS_CA_FILE | no | — | Path to CA PEM; passed via cryptoCredentialsDetails.ca | | MSSQL_TLS_CERT_FILE | no | — | Optional client cert PEM (mutual TLS) | | MSSQL_TLS_KEY_FILE | no | — | Optional client private key PEM | | MSSQL_TLS_KEY_PASSPHRASE | no | — | Passphrase for encrypted client key | | MSSQL_CONNECTION_TIMEOUT_MS | no | (driver default) | Pool connectionTimeout (ms). 0 → unset | | MSSQL_DOMAIN | no | — | Domain login (config.domain for SQL auth; required for MSSQL_AUTH_TYPE=ntlm) | | MSSQL_INSTANCE_NAME | no | — | Named instance (options.instanceName); do not rely on MSSQL_PORT with this set | | MSSQL_MULTI_SUBNET_FAILOVER | no | false | Availability-group style failover hint | | MSSQL_READ_ONLY_INTENT | no | false | Read-only routing for AG secondaries | | MSSQL_MAX_RETRIES_ON_TRANSIENT_ERRORS | no | — | Tedious maxRetriesOnTransientErrors; 0 → unset | | MSSQL_CONNECTION_RETRY_INTERVAL_MS | no | — | Tedious connectionRetryInterval; 0 → unset | | MSSQL_POOL_MAX | no | 10 | Pool max connections | | MSSQL_POOL_MIN | no | 0 | Pool min connections | | MSSQL_POOL_IDLE_TIMEOUT_MS | no | 30000 | pool.idleTimeoutMillis | | MSSQL_APP_NAME | no | — | options.appName (server tracing) | | MSSQL_USE_UTC | no | true | options.useUTC when set | | MSSQL_TDS_VERSION | no | — | 7_1, 7_2, 7_3_A, 7_3_B, or 7_4 | | MSSQL_AUTH_TYPE | no | — | ntlm, azure-active-directory-password, azure-active-directory-access-token, azure-active-directory-service-principal-secret, or unset/default for SQL login | | MSSQL_AZURE_CLIENT_ID | no‡ | — | Azure AD app (client) ID where required | | MSSQL_AZURE_TENANT_ID | no‡ | — | Tenant ID (optional for password auth, defaults common; required for service principal) | | MSSQL_AZURE_CLIENT_SECRET | no‡ | — | Service principal secret | | MSSQL_AZURE_ACCESS_TOKEN | no‡ | — | Pre-obtained token for access-token auth | | MSSQL_ALLOW_WRITES | no | false | If false/unset, blocks common write/DDL/exec patterns in mssql_query (heuristic only) | | MSSQL_QUERY_TIMEOUT_MS | no | (driver default) | Request timeout in ms for the driver. 0 → unset |

† Required for SQL authentication and for auth types that use interactive user login.
‡ Required depending on MSSQL_AUTH_TYPE; see .env.example. NTLM on Node 17+ may need --openssl-legacy-provider (see tedious FAQ).

See also .env.example.

Tools

| Tool | Purpose | |------|--------| | mssql_query | Run T-SQL; returns rows and rowsAffected | | mssql_list_tables | Tables in INFORMATION_SCHEMA | | mssql_describe_table | Column metadata |

When MSSQL_ALLOW_WRITES is unset/false, obvious write/DDL patterns are blocked (heuristic only; use DB permissions for real safety).

Develop

pnpm install
pnpm check
pnpm test
pnpm build && pnpm start
pnpm dev

Use pnpm format to apply Biome formatting fixes and pnpm lint to run lint rules without formatting.

Use a read-only or least-privilege SQL login for day-to-day use.