About MCP Server Development

What is MCP Server Development: Step-by-Step Calculator Tutorial?

MCP Server Development enables AI models to seamlessly integrate with external systems through standardized protocols. This tutorial focuses on building a calculator server as a foundational example, demonstrating how to extend LLM capabilities with custom functions. By following this guide, developers gain hands-on experience in creating reproducible, context-aware services using the MCP framework.

How to Use MCP Server Development: Step-by-Step Calculator Tutorial?

To implement the calculator server, adhere to this structured workflow:

Setup Environment: Leverage Nix for dependency management by installing direnv and Lix, then initialize the project via direnv allow.
Develop the Server: Create Python code defining calculator operations using the MCP SDK, ensuring adherence to protocol specifications.
Test Locally: Utilize the MCP Inspector GUI tool with mcp dev to validate functionality without LLM integration.
Validate: Execute pytest to ensure code reliability and compatibility with MCP standards.

MCP Server Development Features

Key Features of MCP Server Development: Step-by-Step Calculator Tutorial?

Notable advantages include:

Environment Isolation: Nix ensures consistent development across platforms through pre-configured package layers.
Immediate Testing: The MCP Inspector provides a sandboxed interface for iterative debugging without AI system overhead.
Scalable Architecture: The modular design allows easy extension to complex operations beyond basic arithmetic.

Use Cases of MCP Server Development: Step-by-Step Calculator Tutorial?

Practical applications span:

Integrating computational capabilities into AI-powered code editors like Windsurf IDE.
Enabling chatbots to perform real-time calculations without hardcoding logic into models.
Serving as a template for more advanced systems such as database query engines or API connectors.

MCP Server Development FAQ

FAQ from MCP Server Development: Step-by-Step Calculator Tutorial?

Why use Nix instead of virtualenv?: It ensures dependency consistency and eliminates version conflicts across team members.
Can I test without Windsurf Pro?: Yes, the MCP Inspector provides sufficient testing capabilities without requiring premium plans.
How do I deploy this to production?: Containerize the service using Nix's derivation features and expose it via a REST API endpoint.
What if my code fails pytest?: Check MCP protocol adherence first - common issues include mismatched parameter schemas or missing metadata.

Content

How to build an MCP server - Calculator Example

⚠️ work in progress ⚠️

About

"MCP can provide a single, standardized way for AI models to interact with external systems. You write code once and all AI systems can use it." 1

Server

"Servers are the fundamental building block that enriches LLMs with external data and context." 2

Usage

🚧 TODO

MCP Inspector is a handy GUI tool that lets you test your custom MCP server without integrating it with LLM / AI agents.

mcp dev src/mcp_server_calculator/calculator.py

Notes

When using Windsurf IDE as MCP Client, you need to have an Pro Plan to be able to use MCP Servers.

Dev Setup

As we are using Nix in this project for having a reproducible and isolated development environment, there is no need to install Python or any other dependencies. You will get everything you need out of the box. Also there is no need to create a virtual environment in Python using venv or poetry, but you have to be willing to install Nix on your system.

Install direnv
Install Lix
Clone this repository
cd into the directory
Run direnv allow
Run pytest

That's it!

Tech Stack

Python3
Pytest
MCP SDK
MCP CLI
Nix

Resources

Credits

Nix-Setup taken from ical2json

MCP Server Development: Step-by-Step Calculator Tutorial