mcp-tool-builder

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MCP server that creates its own tools as needed

27 stars PythonDeveloper Kits Updated Oct 6, 2025

Documentation

WORK IN PROGRESS - USE WITH CAUTION - Windows

MCP Tool Builder

An MCP server that empowers LLMs to dynamically create new tools through MCP clients such as Claude Desktop.

Features

Create new tools by describing them in natural language
- Requires client restart to use new tools (Claude Desktop)
New tools are saved as python scriptlets in ...\\mcp-tool-builder\\tools
New tool definitions are saved in ...\\mcp-tool-builder\\tools\tools.json

Example tools included at installation

get_bitcoin_price: Fetches current Bitcoin price from CoinGecko
get_weather_forecast: Gets weather for US ZIP codes (uses geopy)

Creating New Tools

Use the create_tool command in Claude Desktop (or suggest strongly!!) to create new tools dynamically

Installation

1. Clone this repository

2. Install dependencies:

bash

cd mcp-tool-builder
uv venv
.venv\Scripts\activate
uv pip install -e .

Usage with Claude Desktop

Add to `claude_desktop_config.json`:

json

{
    "mcpServers": {
        "tool-builder": {
            "command": "uv",
            "args": [
                "--directory", 
                "PATH_TO\\mcp-tool-builder",
                "run",
                "tool-builder"
            ]
        }
    }
}

Frequently asked questions

What is mcp-tool-builder?

mcp-tool-builder is MCP server that creates its own tools as needed

How do I install mcp-tool-builder?

Open the GitHub repository and follow its README. Most MCP servers are added to your client's MCP config, then called by your agent.

Is mcp-tool-builder open source?

Yes — it is hosted on GitHub at https://github.com/hanweg/mcp-tool-builder and has 27 stars.

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