MCP Server for MariaDB (Writable)

A Model Context Protocol server for MariaDB that provides not only read-only access but also optional write capabilities (INSERT, UPDATE, DELETE). This server enables LLMs to inspect database schemas and execute SQL queries based on the permissions you grant.

This project is a fork of the original oleander/mcp-server-mariadb, extended to support mutation operations and granular tool control.

Components

Tools

The server provides several tools that can be individually enabled or disabled:

• mariadb_query_select

  • Execute read-only SQL queries against the connected database.
  • All queries are executed within a READ ONLY transaction.
  • Enabled by default.

• mariadb_query_insert

  • Execute INSERT queries.
  • Disabled by default.

• mariadb_query_update

  • Execute UPDATE queries.
  • Disabled by default.

• mariadb_query_delete

  • Execute DELETE queries.
  • Disabled by default.

Resources

The server provides schema information for each table in the database:

• Table Schemas
  • JSON schema information for each table.
  • Includes column names and data types.
  • Automatically discovered from database metadata.

Configuration

Environment Variables

| Variable | Description | Default | |----------|-------------|---------| | MARIADB_HOST | MariaDB host address | 127.0.0.1 | | MARIADB_PORT | MariaDB port | 3306 | | MARIADB_USER | Database user | root | | MARIADB_PASS | Database password | "" | | MARIADB_DB | Target database name | "" | | ENABLE_MARIADB_QUERY_SELECT | Enable the SELECT tool | true | | ENABLE_MARIADB_QUERY_INSERT | Enable the INSERT tool | false | | ENABLE_MARIADB_QUERY_UPDATE | Enable the UPDATE tool | false | | ENABLE_MARIADB_QUERY_DELETE | Enable the DELETE tool | false | | LOG_LEVEL | Logging level (error, warn, info, debug) | info |

Usage with Claude Desktop

To use this server with the Claude Desktop app, add the following configuration to the mcpServers section of your claude_desktop_config.json:

{
  "mcpServers": {
    "mariadb-writable": {
      "command": "npx",
      "args": ["-y", "@jaesimio/mcp-server-mariadb-writable"],
      "env": {
        "MARIADB_HOST": "127.0.0.1",
        "MARIADB_PORT": "3306",
        "MARIADB_USER": "your_user",
        "MARIADB_PASS": "your_password",
        "MARIADB_DB": "your_db",
        "ENABLE_MARIADB_QUERY_INSERT": "true",
        "ENABLE_MARIADB_QUERY_UPDATE": "true"
      }
    }
  }
}

Logging

All log output is handled by winston and is explicitly redirected to stderr. This ensures that the primary stdout stream remains dedicated to the MCP JSON-RPC protocol, preventing connection issues even when debug logs are enabled.

The log level can be set using the LOG_LEVEL environment variable (e.g., debug).

License

This project is licensed under the MIT License. See the LICENSE.md file for details.