Leap Year MCP Server

This project implements a simple MCP server in Rust for determining if a given year is a leap year according to the rules defined below.

Running the server

Docker

The most straightforward way to run the server is using Docker. You can build the image and run the container with the following command:

docker compose up --build -d

Local

The other option is to run the server locally. You need to have Rust installed on your machine. You can then build and run the server with the following command:

cargo run --release

or you can build the server first and then run it:

cargo build --release
./target/release/leap-year

Server configuration

By default, the server binds to [::]:8080, which means it listens on all available interfaces on port 8080. You can change this by providing a different address and port using the --bind option (see cargo run -- --help for more details).

In order to change the port inside the Docker container, you can modify the docker-compose.yml file to map a different host port to the container's port 8080.

Client configuration

You can interact with the server using any MCP client. The server expects requests to be sent to the /mcp endpoint.

Testing

This project includes unit tests for the leap year logic. You can run the tests with the following command:

cargo test

The tests are also run automatically in the CI pipeline defined in .gitlab-ci.yml.

Credits

Rust MCP SDK - examples and boilerplate code

Assignment

Leap Years

Prior to 1582, the Julian Calendar was in wide use and defined leap years as every year divisible by 4. However, it was found in the late 16^th century that the calendar year had drifted from the solar year by approximately 10 days.

The Gregorian Calendar was defined in order to thin out the number of leap years in order to more closely align the calendar year with the solar year. It was adopted in Papal countries on October 15, 1582, skipping 10 days from the Julian Calendar date. Protestant countries adopted it after some time.

The following diagram shows visually how both calendars work in practice.

User Story

As a user, I want to know if a year is a leap year, so that I can plan for an extra day on February 29^th during those years.

Acceptance Criteria

1. All years divisible by 400 ARE leap years (so, for example, 2000 was indeed a leap year as well as 1600),
2. All years divisible by 100 but not by 400 are NOT leap years (so, for example, 1700, 1800, and 1900 were NOT leap years, NOR will 2100 be a leap year),
3. All years divisible by 4 but not by 100 ARE leap years (e.g., 1976, 1996, 2004),
4. All years not divisible by 4 are NOT leap years (e.g. 2011, 2013, 2014).
5. All years below 1582 divisible by 4 ARE leap years (e.g. 1300, 1400, 1492, 1500, 1580)