tiny_mcp

# TinyMCP A tiny Ruby implementation of the Model Context Protocol (MCP) that makes it easy to create and serve tools locally for AI assistants. ## Installation ```bash gem install tiny_mcp ``` ## Usage Create tools by inheriting from `TinyMCP::Tool`: ```ruby #!/usr/bin/env ruby require 'tiny_mcp' class WeatherTool < TinyMCP::Tool name 'get_weather' desc 'Get current weather for a city' arg :city, :string, 'City name' # required opt :units, :string, 'Temperature units (c/f)' # optional def call(city:, units: 'c') # Your implementation here "Weather in #{city}: 20°C, sunny" end end class TimeTool < TinyMCP::Tool name 'get_time' desc 'Get current time' opt :timezone, :string, 'Timezone name' def call(timezone: 'UTC') Time.now.getlocal(timezone) end end # Serve multiple tools TinyMCP.serve(WeatherTool, TimeTool, server_name: 'my_tool') ``` You can put this in a `bin/mcp` file for example, and make it executable: ```bash chmod +x bin/mcp ``` Then add it to Claude Code: ```bash claude mcp add my-mcp bin/mcp ``` The server reads JSON-RPC requests from stdin and writes responses to stdout. See [examples/](examples/) for more. ## Multiple results and different formats By default TinyMCP assumes you're returning `text` from your call function. If you want to return image, audio, or a bunch of different results, wrap your return value in an array, and TinyMCP will treat your return value as the whole `content` body. Don't forget that binary data such as images and audio needs to be Base64-encoded. ```ruby require 'base64' class MultiModalTool < TinyMCP::Tool name 'get_different_formats' desc 'Get results in different formats' def call [ { type: 'text', text: 'This is a text response' }, { type: 'image', mimeType: 'image/png', data: Base64.strict_encode64(File.binread('image.png')) }, { type: 'audio', mimeType: 'audio/mpeg', data: Base64.strict_encode64(File.binread('audio.mp3')) } ] end end ``` ## Development After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake test` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment. To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and the created tag, and push the `.gem` file to [rubygems.org](https://rubygems.org). ## Contributing Bug reports and pull requests are welcome on GitHub at https://github.com/maxim/tiny_mcp. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [code of conduct](https://github.com/maxim/tiny_mcp/blob/main/CODE_OF_CONDUCT.md). ## License The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT). ## Code of Conduct Everyone interacting in the TinyMCP project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/maxim/tiny_mcp/blob/main/CODE_OF_CONDUCT.md).