nala-db-mcp

A Model Context Protocol (MCP) server for querying databases. Supports SQLite, PostgreSQL, MySQL, and Microsoft SQL Server with read-only access.

Features

• Multiple Database Support: SQLite, PostgreSQL, MySQL, and MS SQL Server
• Read-Only Operations: Safe query execution with DML operation blocking
• MCP Integration: Exposes database querying via the Model Context Protocol
• CSV Output: Query results returned in CSV format
• Environment-Based Configuration: Connection via DATABASE_URL environment variable

Usage

You can use this MCP server with any MCP client, such as Cursor or Claude Desktop.

Configuration in Cursor

Add the following configuration to your MCP settings file (typically in your Cursor settings or .cursorrules):

{
  "mcpServers": {
    "nala-db-mcp": {
      "command": "bunx nala-db-mcp",
      "env": {
        "DATABASE_URL": "mssql://sa:test@localhost:1433/test"
      }
    }
  }
}

Replace the DATABASE_URL value with your database connection string:

• SQLite: sqlite://path/to/database.db
• PostgreSQL: postgres://user:password@localhost:5432/dbname
• MySQL: mysql://user:password@localhost:3306/dbname
• MS SQL Server: mssql://user:password@localhost:1433/dbname

Once configured, the MCP server will be available in your Cursor environment, and you can use the run-query tool to execute read-only SQL queries.

Usage (Local)

For local development or custom integrations, you can install and run the server directly.

Installation

bun install

Configuration

Set your database connection string in the DATABASE_URL environment variable:

# SQLite
export DATABASE_URL="sqlite://path/to/database.db"

# PostgreSQL
export DATABASE_URL="postgres://user:password@localhost:5432/dbname"

# MySQL
export DATABASE_URL="mysql://user:password@localhost:3306/dbname"

# MS SQL Server
export DATABASE_URL="mssql://user:password@localhost:1433/dbname"

Running the Server

bun run start

The MCP server will start and listen on stdio for MCP client connections.

Available Tools

run-query

Executes a read-only SQL query against the configured database.

Input:

• query (string): SQL query to execute. Must be a SELECT query (no INSERT, UPDATE, DELETE, etc.)

Output:

• CSV-formatted query results

Example:

SELECT * FROM users WHERE active = 1

Development

Running Tests

# Run all tests
bun test

# Run specific test file
bun test test/db.test.ts

Linting and Formatting

bun run check

This runs Biome with auto-fix enabled for code formatting and linting.

Project Structure

• index.ts - MCP server setup and tool registration
• src/db.ts - Database connection logic and utilities
• test/db.test.ts - Test suite

Security

• Anything isn't bulletproof, so create a new user with READONLY permissions it's recommended
• All database connections are read-only
• DML operations (INSERT, UPDATE, DELETE, etc.) are blocked via regex validation
• Connection strings support encrypted connections (MS SQL Server uses Encrypt=true)

License

MIT

Built with Bun and the Model Context Protocol SDK