mssql-mcp-node

library3.0.0jsnpmunverified

MCP server for Microsoft SQL Server (v3.0.0) providing 11 introspection and query tools, table resources, and guided prompts. Supports single and multi-database modes, read-only by default with opt-in write support, and runs over stdio or Streamable HTTP. Breaking changes from v2.x include renamed tools, persistent connection pooling, and removal of bespoke REST API.

database

npm install mssql-mcp-node

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · MSSQL-MCP-NODE

mssql-mcp-node

databasejavascriptv3.0.0

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

McpServer

✓ import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'

✗ const { McpServer } = require('@modelcontextprotocol/sdk')

ESM-only package, requires .js extension in import

StdioServerTransport

✓ import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js'

✗ import StdioServerTransport from '@modelcontextprotocol/sdk/server/stdio.js'

Named export, not default

StreamableHTTPServerTransport

✓ import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js'

✗ import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/http.js'

Note the 'streamable' prefix and exact filename

Creates an MCP server for MSSQL with one tool and connects over stdio.

import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js"; import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js"; const server = new McpServer({ name: "mssql", version: "3.0.0" }); server.tool("list_databases", {}, async () => { return { content: [{ type: "text", text: "Databases listed" }] }; }); const transport = new StdioServerTransport(); await server.connect(transport);

Debug

Known issues

breakingexecute_sql renamed to execute_read_query + execute_write_query

fix

Use execute_read_query for read-only and execute_write_query for writes (requires MSSQL_ENABLE_WRITES=true)

affects: >=3.0.0

breakingget_table_schema renamed to describe_table

fix

Call describe_table instead of get_table_schema

affects: >=3.0.0

breakingConnection pool now per-dbKey and reused; old code each call created a new pool

fix

No action needed, but connections are now reused. Ensure pool cleanup on server shutdown.

affects: >=3.0.0

breakingBespoke REST API removed in favor of Streamable HTTP at POST /mcp

fix

Switch to MCP client sending POST requests to /mcp endpoint

affects: >=3.0.0

gotchaMSSQL_ENABLE_WRITES must be set to true to allow write queries; default is read-only

fix

Set environment variable MSSQL_ENABLE_WRITES=true to enable execute_write_query

affects: >=3.0.0

gotchaMulti-database mode conflicts with single-database mode if both sets of env vars are present

fix

Use only single-database MSSQL_* variables OR multi-database MSSQL_<NAME>_* variables, not both

affects: >=3.0.0

Errors

Common errors & fixes

Error: Cannot find module '@modelcontextprotocol/sdk'

Missing dependency or incorrect install

fix

npm install @modelcontextprotocol/sdk

TypeError: Class extends value undefined is not a constructor or null

Incorrect import of McpServer or Transport

fix

Ensure correct import path: import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'

Error: listen EADDRINUSE :::3000

Port 3000 already in use

fix

Kill the process using port 3000 or set a different port via environment variable

Upgrade

Version history

3.0.0latest on npm

Audit

Dependencies

@modelcontextprotocol/sdkrequiredCore SDK for implementing the MCP protocol

Agent activity

2 hits · last 30 days

node

Resources

githubhttps://github.com/mihai-dulgheru/mssql-mcp-node ↗

packagemssql-mcp-node ↗

homepagehttps://github.com/mihai-dulgheru/mssql-mcp-node#readme ↗