Character Counter MCP Server - Python Quickstart

A simple example of creating an MCP server using FastMCP and Python, designed to work with Smithery.

What This Does

This server provides a character counter tool called count_character that counts how many times a specific character appears in a given text. You'll test it using the Smithery Playground for interactive development.

Prerequisites

• Python 3.12 or higher
• A Python package manager (uv recommended, but pip, poetry, etc. also work)
• Node.js and npx (optional, for Smithery Playground)

Quick Start

1. Clone the repository:

   bash

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   git clone https://github.com/smithery-ai/smithery-cookbook.git
   cd smithery-cookbook/servers/python/quickstart

2. Install dependencies:

   With uv (recommended):

   bash

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   uv sync

   With poetry:

   bash

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   poetry install

   With pip:

   bash

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   pip install -r requirements.txt

3. Run the server:

   You have two options:

   Option A: Just run the server

   bash

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   # With uv
   uv run smithery dev
   # or use the shorter script alias:
   uv run dev
   
   # With poetry
   poetry run smithery dev
   # or use the shorter script alias:
   poetry run dev
   
   # With pip (after installing dependencies)
   smithery dev

   This starts the MCP server on http://localhost:8081 and keeps it running.

   Option B: Run server + open playground (recommended for testing)

   bash

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   # With uv
   uv run smithery playground
   # or use the shorter script alias:
   uv run playground
   
   # With poetry
   poetry run smithery playground
   # or use the shorter script alias:
   poetry run playground
   
   # With pip (after installing dependencies)
   smithery playground

   This starts the MCP server AND automatically opens the Smithery Playground in your browser where you can:

   • Interact with your MCP server in real-time
   • Test the count_character tool with different text and characters
   • See the complete request/response flow
   • Debug and iterate on your MCP tools quickly

Testing the Character Counter

Try asking: "How many r's are in strawberry?"

4. Deploy to Smithery: To deploy your MCP server:
   • Push your code to GitHub (make sure to include the smithery.yaml)
   • Connect your repository at https://smithery.ai/new

Your server will be available over HTTP and ready to use with any MCP-compatible client!

Stopping the Server

Press Ctrl+C in the terminal to stop the server.