MCP SQL Server (Development)

A professional MCP server to connect any MCP-compatible LLM to a SQL database and execute:

• Queries (SELECT, WITH, SHOW, etc.)

• DML (INSERT, UPDATE, DELETE)

• DDL (CREATE, ALTER, and optionally DROP/TRUNCATE)

This server is designed for personal use in assisted development.

Features

• MCP protocol via stdio (compatible with MCP clients).

• Multi-engine connection via SQLAlchemy (sqlite, postgresql, mysql, mssql, etc.).

• MCP tools focused on daily operations:

  • sql_capabilities

  • sql_list_tables

  • sql_describe_table

  • sql_run

  • sql_run_script

• Destructive DDL blocking by default (DROP/TRUNCATE blocked).

• Configurable row and statement limits per script.

Related MCP server: FastMCP MySQL Server

Installation

python -m venv .venv
source .venv/bin/activate
pip install -e .

Configuration (environment variables)

Prefix: MCP_SQL_

• MCP_SQL_DATABASE_URL: SQLAlchemy URL. Default: sqlite:///./dev.db

• MCP_SQL_MAX_ROWS: maximum rows returned per query. Default: 200

• MCP_SQL_MAX_SCRIPT_STATEMENTS: maximum statements per script. Default: 100

• MCP_SQL_ALLOW_DESTRUCTIVE_DDL: true/false to allow DROP and TRUNCATE. Default: false

Example

export MCP_SQL_DATABASE_URL='postgresql+psycopg://dev_user:dev_pass@localhost:5432/devdb'
export MCP_SQL_MAX_ROWS=500
export MCP_SQL_ALLOW_DESTRUCTIVE_DDL=false

Running the server

mcp-sql-server

You can also run it as a module:

python -m mcp_sql_server.server

Double-click startup on Windows

The file start_mcp_sql_server.bat is included to facilitate startup:

1. Automatically creates .venv (if it doesn't exist).

2. Installs/updates dependencies.

3. Starts the MCP server.

Just double-click that .bat file.

Configuration in an MCP client (generic example)

{
  "mcpServers": {
    "sql-dev": {
      "command": "mcp-sql-server",
      "env": {
        "MCP_SQL_DATABASE_URL": "sqlite:///./dev.db",
        "MCP_SQL_MAX_ROWS": "200",
        "MCP_SQL_ALLOW_DESTRUCTIVE_DDL": "false"
      }
    }
  }
}

Recommended workflow

1. sql_capabilities to verify active configuration.

2. sql_list_tables to explore the schema.

3. sql_describe_table to inspect metadata.

4. sql_run for specific queries or DML.

5. sql_run_script for batches of controlled changes.

Best practices for assisted development

• Use database users with minimal privileges.

• Work on a local development DB or disposable snapshot.

• Keep MCP_SQL_ALLOW_DESTRUCTIVE_DDL=false by default.

• Version structural changes with migrations.

Security note

This project is not hardened for production. It is oriented toward local productivity in development environments.

Claude in VS Code guide

Check README_CLAUDE_VSCODE.md for a complete configuration and usage example.