MSSQL LocalDB MCP

io.github.hermessilvaPublished by GitHub account hermessilvav0.1.0Updated Oct 24, 2026

MCP server for SQL Server Express LocalDB on Windows: manage instances, run T-SQL, discover DBs

VerifiedSTDIODesktop onlyDatabasesDeveloper Tools

Overview

AI-generated overview

A Windows-only MCP server that gives an assistant control over SQL Server Express LocalDB instances: create and manage them, run T-SQL, and attach loose .mdf/.m

What you can do
Create, start, stop and manage SQL Server Express LocalDB instances on the machine. Run T-SQL scripts and queries against a LocalDB database, with configurable timeouts and row limits. Find loose database files in allowed project folders and attach them. Inspect database schema and structure.
When to use it
Useful for Windows developers working with SQL Server Express LocalDB who want an assistant to set up instances, attach project database files, run scripts and inspect schema without opening SSMS. Not intended for remote or multi-database servers.
Requirements
Windows with SQL Server Express LocalDB installed and SqlLocalDB.exe on PATH. A compatible MCP client. A config.toml under %APPDATA% with at least one allowed scan root, otherwise folder scanning refuses to run. Distributed as a bundled Windows binary; building from source needs Rust.
Before you install
The server can run arbitrary T-SQL, including destructive statements; the README says DROP, TRUNCATE, DELETE and ALTER require explicit confirmation, but review what the assistant executes. Folder scanning is limited to allowlisted roots in config.toml. Uses Windows Integrated Authentication only, so the assistant acts with your Windows account's database rights.

Installation

In SourceWeft

  1. Open MSSQL LocalDB MCP in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Desktop only via STDIO. STDIO servers start a local process, so they need the SourceWeft desktop host.

Other MCP clients

Follow the launch instructions in the repository.

README

mssql-localdb-mcp

Rust MCP server for SQL Server Express LocalDB on Windows. Gives AI agents (Claude Desktop, Claude Code, and any MCP client) full control over LocalDB instances: create/manage instances, run any T-SQL script, find loose database files in project folders and attach them, introspect schema.

Status: MVP (Phase 1) functional and tested against real LocalDB — see docs/PLANNING.md for the roadmap and current phase.

Why

Existing MCP tools for SQL Server assume an already-configured remote server and require an external runtime (Python, .NET, Node). This project is:

  • Single Rust binary, no external runtime, no Docker.
  • LocalDB-focused: local dev workflow — find a loose .mdf in a project folder, attach it, run a script, no need to open SSMS.
  • Windows-only by design, not a generic multi-database abstraction.

Requirements

  • Windows with SQL Server Express LocalDB installed (SqlLocalDB.exe on PATH).
  • A compatible MCP client (Claude Desktop, Claude Code, etc.).

Installation

Via MCP Registry

Published on the official MCP Registry as io.github.hermessilva/mssql-localdb-mcp. Install through any MCP client that supports the registry.

Via VS Code extension

The vscode-extension/ directory packages the server as a VS Code extension that registers it automatically through the MCP provider API (VS Code 1.101+), with the Windows binary bundled — nothing to download or configure by hand. Build the .vsix locally with:

powershell
./build-vsix.ps1                 # bumps the build segment; -Version x.y.z or -NoBump to control itcode --install-extension .\mssql-localdb-mcp-1.0.1-win32-x64.vsix

The extension has its own version line, independent from Cargo.toml — the crate version is what the vX.Y.Z tag and the MCP Registry publish.

Via Claude Code plugin

The claude-plugin/ directory in this repo is a self-contained Claude Code plugin (bundles the Windows binary directly, no separate download). Load it directly with:

powershell
claude --plugin-dir path\to\LocalDB-MCP\claude-plugin

Submitted to the claude-community marketplace for review — once approved, install it with claude plugin marketplace add anthropics/claude-plugins-community followed by claude plugin install mssql-localdb-mcp@claude-community.

From source

Requires Rust and LocalDB installed.

powershell
git clone https://github.com/hermessilva/LocalDB-MCP.gitcd LocalDB-MCPcargo build --release

Binary at target\release\mssql-localdb-mcp.exe.

Configure config.toml

db_scan_folder requires at least one explicitly allowed root — without it, the tool refuses to run. Create %APPDATA%\mssql-localdb-mcp\config.toml:

toml
# Windows paths in TOML need single quotes (literal string) — double# quotes interpret \U... as a unicode escape and break parsing.scan_allowlist = ['C:\Users\YourUser\source\repos']scan_max_depth = 6default_query_timeout_secs = 30default_max_rows = 1000

Configure in your MCP client

Claude Desktop / Claude Code (claude_desktop_config.json or equivalent):

json
{  "mcpServers": {    "mssql-localdb": {      "command": "C:\\path\\to\\LocalDB-MCP\\target\\release\\mssql-localdb-mcp.exe"    }  }}

Claude Code via CLI:

powershell
claude mcp add mssql-localdb -- "C:\path\to\LocalDB-MCP\target\release\mssql-localdb-mcp.exe"

After that, the agent has access to the localdb_*, sql_*, and db_* tools — see docs/MCP_SPEC.md for the full list.

Documentation

Security — read before using

  • Windows Integrated Authentication only (no SQL Auth).
  • Every destructive action (DROP, TRUNCATE, DELETE, ALTER, etc.) requires explicit confirmation (confirm: true) — never executes silently.
  • Database discovery (db_scan_folder) only scans folders explicitly allowed in config.toml (allowlist).
  • Full detail in docs/SECURITY.md.

License

MIT.

Source: README.md at commit c2a1185

Tools

0
SourceWeft has not started this package in its sandbox yet, so its tools are not known.

Version history

1
  1. v0.1.0LatestSep 16, 2026

Score

50% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 days25 pts

    Keep the endpoint answering the MCP handshake; SourceWeft probes it every 30 days.

  • Auth declared10 pts

    Declare the credential headers in the registry entry, or keep the endpoint answering the probe so its auth can be classified.

  • Tools listed15 pts

    Answer tools/list without a credential, or ship a package that starts in a sandbox without one.

  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts