@warnyin/mssql-mcp

A Model Context Protocol (MCP) server for managing Microsoft SQL Server. Exposes read-only and administrative tools over stdio, so it can be launched directly by any MCP-compatible client (Claude Desktop, Claude Code, MCP Inspector, etc.) via npx.

Features

• List & describe — databases, schemas, tables, views, stored procedures, functions, indexes, foreign keys.
• Get definitions — source T-SQL for views, procedures, and functions.
• Query — safe SELECT / WITH execution with row caps and pagination guidance.
• Execute — full T-SQL (INSERT, UPDATE, DELETE, DDL) when needed; opt-in disabled via MSSQL_READONLY=true.
• Server info — version, edition, current login, collation.

Quickstart

Run via npx

MSSQL_SERVER=localhost \
MSSQL_USER=sa \
MSSQL_PASSWORD='Your_Strong_Password' \
MSSQL_DATABASE=master \
npx -y @warnyin/mssql-mcp

Run from source

npm install
npm run build
MSSQL_SERVER=localhost MSSQL_USER=sa MSSQL_PASSWORD='Your_Strong_Password' node dist/index.js

Test with MCP Inspector

npx -y @modelcontextprotocol/inspector \
  --env MSSQL_SERVER=localhost \
  --env MSSQL_USER=sa \
  --env MSSQL_PASSWORD='Your_Strong_Password' \
  node dist/index.js

Configuration

All configuration is via environment variables.

| Variable | Required | Default | Description | | --- | --- | --- | --- | | MSSQL_SERVER | ✅ | — | Server hostname or IP. | | MSSQL_USER | ✅ | — | SQL login. | | MSSQL_PASSWORD | ✅ | — | SQL login password. | | MSSQL_DATABASE | | (login default) | Default database for queries. | | MSSQL_PORT | | 1433 | TCP port. | | MSSQL_INSTANCE | | — | Named instance (e.g. SQLEXPRESS). | | MSSQL_ENCRYPT | | true | Enable TLS. | | MSSQL_TRUST_SERVER_CERTIFICATE | | false | Accept self-signed certs (dev only). | | MSSQL_CONNECTION_TIMEOUT_MS | | 15000 | Connect timeout. | | MSSQL_REQUEST_TIMEOUT_MS | | 30000 | Per-request timeout. | | MSSQL_READONLY | | false | When true, disables mssql_execute. |

Claude Desktop / Claude Code config

Add this entry to your MCP servers config (claude_desktop_config.json or your Claude Code MCP config):

{
  "mcpServers": {
    "mssql": {
      "command": "npx",
      "args": ["-y", "@warnyin/mssql-mcp"],
      "env": {
        "MSSQL_SERVER": "localhost",
        "MSSQL_USER": "sa",
        "MSSQL_PASSWORD": "Your_Strong_Password",
        "MSSQL_DATABASE": "master"
      }
    }
  }
}

Tools

| Tool | Read-only | Description | | --- | --- | --- | | mssql_list_databases | ✅ | List databases on the instance. | | mssql_list_schemas | ✅ | List user schemas in a database. | | mssql_list_tables | ✅ | List tables, optionally filtered by schema, with row counts. | | mssql_describe_table | ✅ | Columns, PK, FKs, and indexes for a table or view. | | mssql_list_views | ✅ | List views. | | mssql_list_procedures | ✅ | List stored procedures and user-defined functions. | | mssql_get_object_definition | ✅ | T-SQL source of a view / procedure / function. | | mssql_query | ✅ | Run a SELECT / WITH query. Capped at 100 rows by default (max 10000). | | mssql_execute | ❌ | Run any T-SQL — disabled when MSSQL_READONLY=true. | | mssql_server_info | ✅ | Version, edition, hostname, current login, collation. |

Every tool supports response_format: 'markdown' | 'json' (defaults to markdown).

Safety notes

• mssql_query rejects statements that don't begin with SELECT or WITH (after leading comments/whitespace).
• mssql_execute is marked destructiveHint: true and is fully disabled when MSSQL_READONLY=true.
• Responses are capped at 25 000 characters; results beyond that are truncated and truncated: true is reported in the structured response.
• The server logs to stderr only (per stdio MCP convention).

License

MIT