MySQL Database Access MCP Server

This MCP server provides read-only access to MySQL databases. It allows you to:

• List available databases
• List tables in a database
• Describe table schemas
• Execute read-only SQL queries

Security Features

• Read-only access: Only SELECT, SHOW, DESCRIBE, and EXPLAIN statements are allowed; file-capable SELECT INTO and LOAD_FILE forms are rejected
• Query validation: Prevents SQL injection and blocks any data modification attempts
• Query timeout: Prevents long-running queries from consuming resources
• Row limit: Prevents excessive data return
• Exact large numbers: BIGINT and DECIMAL values are returned as strings to prevent precision loss

Installation

1. Install using one of these methods:

Install from NPM

# Install globally
npm install -g mysql-mcp-server

# Or install locally in your project
npm install mysql-mcp-server

Build from Source

# Clone the repository
git clone https://github.com/dpflucas/mysql-mcp-server.git
cd mysql-mcp-server

# Install dependencies and build
npm install
npm run build

2. Configure environment variables

The server requires the following environment variables:

• MYSQL_HOST: Database server hostname
• MYSQL_PORT: Database server port (default: 3306)
• MYSQL_USER: Database username
• MYSQL_PASSWORD: Database password (optional, but recommended for secure connections)
• MYSQL_DATABASE: Default database name (optional)

3. Add to MCP settings

Add the following configuration to your MCP settings file:

If you installed via npm (Option 1):

{
  "mcpServers": {
    "mysql": {
      "command": "npx",
      "args": ["mysql-mcp-server"],
      "env": {
        "MYSQL_HOST": "your-mysql-host",
        "MYSQL_PORT": "3306",
        "MYSQL_USER": "your-mysql-user",
        "MYSQL_PASSWORD": "your-mysql-password",
        "MYSQL_DATABASE": "your-default-database"
      },
      "disabled": false,
      "autoApprove": []
    }
  }
}

If you built from source (Option 2):

{
  "mcpServers": {
    "mysql": {
      "command": "node",
      "args": ["/path/to/mysql-mcp-server/build/index.js"],
      "env": {
        "MYSQL_HOST": "your-mysql-host",
        "MYSQL_PORT": "3306",
        "MYSQL_USER": "your-mysql-user",
        "MYSQL_PASSWORD": "your-mysql-password",
        "MYSQL_DATABASE": "your-default-database"
      },
      "disabled": false,
      "autoApprove": []
    }
  }
}

Available Tools

list_databases

Lists all accessible databases on the MySQL server.

Parameters: None

Example:

{
  "server_name": "mysql",
  "tool_name": "list_databases",
  "arguments": {}
}

list_tables

Lists all tables in a specified database.

Parameters:

• database (optional): Database name (uses default if not specified)

Example:

{
  "server_name": "mysql",
  "tool_name": "list_tables",
  "arguments": {
    "database": "my_database"
  }
}

describe_table

Shows the schema for a specific table.

Parameters:

• database (optional): Database name (uses default if not specified)
• table (required): Table name

Example:

{
  "server_name": "mysql",
  "tool_name": "describe_table",
  "arguments": {
    "database": "my_database",
    "table": "my_table"
  }
}

execute_query

Executes a read-only SQL query.

Parameters:

• query (required): SQL query (only SELECT, SHOW, DESCRIBE, and EXPLAIN statements are allowed)
• database (optional): Database name (uses default if not specified)

Example:

{
  "server_name": "mysql",
  "tool_name": "execute_query",
  "arguments": {
    "database": "my_database",
    "query": "SELECT * FROM my_table LIMIT 10"
  }
}

Advanced Connection Pool Configuration

For more control over the MySQL connection pool behavior, you can configure additional parameters:

{
  "mcpServers": {
    "mysql": {
      "command": "npx",
      "args": ["mysql-mcp-server"],
      "env": {
        "MYSQL_HOST": "your-mysql-host",
        "MYSQL_PORT": "3306",
        "MYSQL_USER": "your-mysql-user",
        "MYSQL_PASSWORD": "your-mysql-password",
        "MYSQL_DATABASE": "your-default-database",
        
        "MYSQL_CONNECTION_LIMIT": "10",
        "MYSQL_QUEUE_LIMIT": "0",
        "MYSQL_CONNECT_TIMEOUT": "10000",
        "MYSQL_IDLE_TIMEOUT": "60000",
        "MYSQL_MAX_IDLE": "10"
      },
      "disabled": false,
      "autoApprove": []
    }
  }
}

These advanced options allow you to:

• MYSQL_CONNECTION_LIMIT: Control the maximum number of connections in the pool (default: 10)
• MYSQL_QUEUE_LIMIT: Set the maximum number of connection requests to queue (default: 0, unlimited)
• MYSQL_CONNECT_TIMEOUT: Adjust the connection timeout in milliseconds (default: 10000)
• MYSQL_IDLE_TIMEOUT: Configure how long a connection can be idle before being released (in milliseconds)
• MYSQL_MAX_IDLE: Set the maximum number of idle connections to keep in the pool

Testing

The server includes test scripts to verify functionality with your MySQL setup:

1. Setup Test Database

This script creates a test database, table, and sample data:

# Set your MySQL credentials as environment variables
export MYSQL_HOST=localhost
export MYSQL_PORT=3306
export MYSQL_USER=your_username
export MYSQL_PASSWORD=your_password

# Run the setup script
npm run test:setup

2. Test MCP Tools

This script tests each of the MCP tools against the test database:

# Set your MySQL credentials as environment variables
export MYSQL_HOST=localhost
export MYSQL_PORT=3306
export MYSQL_USER=your_username
export MYSQL_PASSWORD=your_password
export MYSQL_DATABASE=mcp_test_db

# Run the tools test script
npm run test:tools

3. Run All Tests

To run both setup and tool tests:

# Set your MySQL credentials as environment variables
export MYSQL_HOST=localhost
export MYSQL_PORT=3306
export MYSQL_USER=your_username
export MYSQL_PASSWORD=your_password

# Run all tests
npm test

Troubleshooting

If you encounter issues:

1. Check the server logs for error messages
2. Verify your MySQL credentials and connection details
3. Ensure your MySQL user has appropriate permissions
4. Check that your query is read-only and properly formatted

License

This project is licensed under the MIT License - see the LICENSE file for details.