mcp-server-duckdb

A Model Context Protocol (MCP) server implementation for DuckDB, providing database interaction capabilities through MCP tools. It would be interesting to have LLM analyze it. DuckDB is suitable for local analysis.

Overview

This server enables interaction with a DuckDB database through the Model Context Protocol, allowing for database operations like querying, table creation, and schema inspection.

Components

Resources

Currently, no custom resources are implemented.

Prompts

Currently, no custom prompts are implemented.

Tools

The server implements the following database interaction tools:

• read-query: Execute SELECT queries to read data from the database
  • Input: query (string) - Must be a SELECT statement
  • Output: Query results as text
• write-query: Execute INSERT, UPDATE, or DELETE queries to modify data
  • Input: query (string) - Must be a non-SELECT statement
  • Output: Query results as text
• create-table: Create new tables in the database
  • Input: query (string) - Must be a CREATE TABLE statement
  • Output: Success confirmation message
• list-tables: List all tables in the database
  • Input: None required
  • Output: List of tables from information_schema
• describe-table: Get schema information for a specific table
  • Input: table_name (string) - Name of the table to describe
  • Output: Table schema information

Note: When the server is running in readonly mode, the following tools are disabled to prevent any write operations:

• write-query
• create-table

This ensures that the Language Model (LLM) cannot perform any modifications to the database, maintaining data integrity and preventing unintended changes.

Configuration

Required Parameters

• db-path (string): Path to the DuckDB database file
  • The server will automatically create the database file and parent directories if they don't exist

Optional Parameters

• --readonly: Run server in read-only mode
  • Description: When this flag is set, the server operates in read-only mode. This means:
    • The DuckDB database will be opened with read_only=True, preventing any write operations.
    • If the specified database file does not exist, it will not be created.
    • Security Benefit: Prevents the Language Model (LLM) from performing any write operations, ensuring that the database remains unaltered.
  • Reference: For more details on read-only connections in DuckDB, see the DuckDB Python API documentation.

Installation

Claude Desktop Integration

Configure the MCP server in Claude Desktop's configuration file:

MacOS

Location: ~/Library/Application Support/Claude/claude_desktop_config.json

Windows

Location: %APPDATA%/Claude/claude_desktop_config.json

• Note: ~/mcp-server-duckdb/data/data.db should be replaced with the actual path to the DuckDB database file.

Development

Prerequisites

• Python with uv package manager
• DuckDB Python package
• MCP server dependencies

Debugging

Debugging MCP servers can be challenging due to their stdio-based communication. We recommend using the MCP Inspector for the best debugging experience.

Using MCP Inspector

1. Install the inspector using npm:

2. Open the provided URL in your browser to access the debugging interface

The inspector provides visibility into:

• Request/response communication
• Tool execution
• Server state
• Error messages