Internal Release v0.1.1

- implement `Prompt`
- adjust Tool approach
- update readme for tool calling
- document usage of `Prompt`

.gitattributes

@@ -0,0 +1,4 @@
+# See https://git-scm.com/docs/gitattributes for more about git attribute files.
+
+# Mark any vendored files as having been vendored.
+vendor/* linguist-vendored

.github/workflows/ci.yml

@@ -0,0 +1,22 @@
+name: CI
+on: [push, pull_request]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        entry:
+          - { ruby: 3.2, allowed-failure: false }
+          - { ruby: 3.3, allowed-failure: false }
+          - { ruby: 3.4, allowed-failure: false }
+          - { ruby: head, allowed-failure: true }
+    name: Test Ruby ${{ matrix.entry.ruby }}
+    steps:
+      - uses: actions/checkout@v3
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.entry.ruby }}
+          bundler-cache: true
+      - run: bundle exec rake test
+        continue-on-error: ${{ matrix.entry.allowed-failure }}

.gitignore

@@ -0,0 +1,8 @@
+/.bundle/
+/.yardoc
+/_yardoc/
+/coverage/
+/doc/
+/pkg/
+/spec/reports/
+/tmp/

.rubocop.yml

@@ -0,0 +1,2 @@
+inherit_gem:
+  rubocop-shopify: rubocop.yml

.ruby-version

@@ -0,0 +1 @@
+3.3.0

CODE_OF_CONDUCT.md

@@ -0,0 +1,74 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as
+contributors and maintainers pledge to making participation in our project and
+our community a harassment-free experience for everyone, regardless of age, body
+size, disability, ethnicity, gender identity and expression, level of experience,
+nationality, personal appearance, race, religion, or sexual identity and
+orientation.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment
+include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or
+advances
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic
+  address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable
+behavior and are expected to take appropriate and fair corrective action in
+response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or
+reject comments, commits, code, wiki edits, issues, and other contributions
+that are not aligned to this Code of Conduct, or to ban temporarily or
+permanently any contributor for other behaviors that they deem inappropriate,
+threatening, offensive, or harmful.
+
+## Scope
+
+This Code of Conduct applies both within project spaces and in public spaces
+when an individual is representing the project or its community. Examples of
+representing a project or community include using an official project e-mail
+address, posting via an official social media account, or acting as an appointed
+representative at an online or offline event. Representation of a project may be
+further defined and clarified by project maintainers.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported by contacting the project team at topher.bullock@shopify.com. All
+complaints will be reviewed and investigated and will result in a response that
+is deemed necessary and appropriate to the circumstances. The project team is
+obligated to maintain confidentiality with regard to the reporter of an incident.
+Further details of specific enforcement policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good
+faith may face temporary or permanent repercussions as determined by other
+members of the project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4,
+available at [http://contributor-covenant.org/version/1/4][version]
+
+[homepage]: http://contributor-covenant.org
+[version]: http://contributor-covenant.org/version/1/4/

Gemfile

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+source "https://rubygems.org"
+
+# Specify runtime dependencies in the gemspec
+gemspec
+
+# Specify development dependencies below
+gem "minitest", "~> 5.1", require: false
+gem "rake", "~> 13.0"
+gem "rubocop-shopify", require: false
+
+gem "activesupport"
+gem "minitest-reporters"
+gem "mocha"

Gemfile.lock

@@ -0,0 +1,95 @@
+PATH
+  remote: .
+  specs:
+    model_context_protocol (0.1.1)
+      activesupport
+
+GEM
+  remote: https://rubygems.org/
+  specs:
+    activesupport (8.0.2)
+      base64
+      benchmark (>= 0.3)
+      bigdecimal
+      concurrent-ruby (~> 1.0, >= 1.3.1)
+      connection_pool (>= 2.2.5)
+      drb
+      i18n (>= 1.6, < 2)
+      logger (>= 1.4.2)
+      minitest (>= 5.1)
+      securerandom (>= 0.3)
+      tzinfo (~> 2.0, >= 2.0.5)
+      uri (>= 0.13.1)
+    ansi (1.5.0)
+    ast (2.4.3)
+    base64 (0.2.0)
+    benchmark (0.4.0)
+    bigdecimal (3.1.9)
+    builder (3.3.0)
+    concurrent-ruby (1.3.5)
+    connection_pool (2.5.3)
+    drb (2.2.1)
+    i18n (1.14.7)
+      concurrent-ruby (~> 1.0)
+    json (2.11.3)
+    language_server-protocol (3.17.0.4)
+    lint_roller (1.1.0)
+    logger (1.7.0)
+    minitest (5.25.5)
+    minitest-reporters (1.7.1)
+      ansi
+      builder
+      minitest (>= 5.0)
+      ruby-progressbar
+    mocha (2.7.1)
+      ruby2_keywords (>= 0.0.5)
+    parallel (1.27.0)
+    parser (3.3.8.0)
+      ast (~> 2.4.1)
+      racc
+    prism (1.4.0)
+    racc (1.8.1)
+    rainbow (3.1.1)
+    rake (13.2.1)
+    regexp_parser (2.10.0)
+    rubocop (1.75.5)
+      json (~> 2.3)
+      language_server-protocol (~> 3.17.0.2)
+      lint_roller (~> 1.1.0)
+      parallel (~> 1.10)
+      parser (>= 3.3.0.2)
+      rainbow (>= 2.2.2, < 4.0)
+      regexp_parser (>= 2.9.3, < 3.0)
+      rubocop-ast (>= 1.44.0, < 2.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (>= 2.4.0, < 4.0)
+    rubocop-ast (1.44.1)
+      parser (>= 3.3.7.2)
+      prism (~> 1.4)
+    rubocop-shopify (2.17.0)
+      rubocop (~> 1.62)
+    ruby-progressbar (1.13.0)
+    ruby2_keywords (0.0.5)
+    securerandom (0.4.1)
+    tzinfo (2.0.6)
+      concurrent-ruby (~> 1.0)
+    unicode-display_width (3.1.4)
+      unicode-emoji (~> 4.0, >= 4.0.4)
+    unicode-emoji (4.0.4)
+    uri (1.0.3)
+
+PLATFORMS
+  arm64-darwin-23
+  ruby
+
+DEPENDENCIES
+  activesupport
+  minitest (~> 5.1)
+  minitest-reporters
+  mocha
+  model_context_protocol!
+  rake (~> 13.0)
+  rubocop-shopify
+
+BUNDLED WITH
+   2.5.9

LICENSE.txt

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2025 TODO: Write your name
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

README.md

@@ -0,0 +1,102 @@
+# Model Context Protocol
+
+A Ruby gem implementing Model Context Protocol + JSON RPC 2.0 spec
+
+## Overview
+
+Model Context Protocol provides a standardized way to interact with language models through a JSON RPC 2.0 interface.
+
+It handles request/response formatting, error handling, and tool integrations in a type-safe manner using Sorbet.
+
+See https://spec.modelcontextprotocol.io/specification/
+
+This implementation breaks from the transport examples in the spec as it implements a POST-based JSON RPC call rather
+than a stateful SSE transport.
+
+## MCP Server
+
+The `ModelContextProtocol::Server` class is the core component that handles JSON-RPC requests and responses.
+It implements the Model Context Protocol specification, handling model context requests and responses.
+
+### Key Features
+
+- Implements JSON-RPC 2.0 message handling
+- Supports protocol initialization and capability negotiation
+- Manages tool registration and invocation
+- Provides type-safe request/response handling using Sorbet
+
+### Supported Methods
+
+- `initialize` - Initializes the protocol and returns server capabilities
+- `ping` - Simple health check that returns "pong"
+- `tools/list` - Lists all registered tools and their schemas
+- `tools/call` - Invokes a specific tool with provided arguments
+- `prompts/list` - Lists all registered prompts and their schemas
+- `prompts/get` - Retrieves a specific prompt by name
+
+### Usage
+
+Implement an `ApplicationController` which calls the `Server#handle` method, eg
+
+```ruby
+module ModelContextProtocol
+  class ApplicationController < ActionController::Base
+
+    sig { void }
+    def index
+      server = ModelContextProtocol::Server.new(
+        name: "my_server",
+        tools: [someTool, anotherTool],
+        prompts: [myPrompt]
+      )
+      render(json: server.handle(request.body.read).to_h)
+    end
+  end
+end
+```
+
+## Tools
+
+MCP spec includes [Tools](https://modelcontextprotocol.io/docs/concepts/tools) which provide functionality to LLM apps.
+
+This gem provides a `ModelContextProtocol::Tool` class that can be instantiated to create tools.
+
+Tools can be passed into the `ModelContextProtocol::Server` constructor to register them with the server.
+
+### Example Tool Implementation
+
+The `Tool` class allows creating tools that can be used within the model context.
+To create a tool, instantiate the class with the required parameters and an optional block:
+
+```ruby
+tool = ModelContextProtocol::Tool.new(name: "my_tool", description: "This tool performs specific functionality...") do |args|
+  # Implement the tool's functionality here
+  result = process_something(args["parameter_name"])
+  ModelContextProtocol::Tool::Response.new([{ type: "text", text: result }], false )
+end
+```
+
+## Prompts
+
+MCP spec includes
+[Prompts](https://modelcontextprotocol.io/docs/concepts/prompts), `Prompts` enable servers to define reusable prompt
+templates and workflows that clients can easily surface to users and LLMs
+
+The `Prompt` class allows creating prompts that can be used within the model context.
+
+To create a prompt, instantiate the class with the required parameters and an optional block:
+
+```ruby
+prompt = ModelContextProtocol::Prompt.new(name: "my_prompt", description: "This prompt performs specific functionality...") do |args|
+  # Implement the prompt's functionality here
+  result = template_something(args["parameter_name"])
+  ModelContextProtocol::Prompt::Response.new([{ type: "text", text: result }], false )
+end
+```
+
+
+
+
+## Releases
+
+TODO

Rakefile

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+require "bundler/gem_tasks"
+require "rake/testtask"
+
+Rake::TestTask.new(:test) do |t|
+  t.ruby_opts = ["-W0", "-W:deprecated"]
+  t.libs << "test"
+  t.libs << "lib"
+  t.test_files = FileList["test/**/*_test.rb"]
+end
+
+require "rubocop/rake_task"
+
+RuboCop::RakeTask.new
+
+task default: [:test, :rubocop]

bin/console

@@ -0,0 +1,15 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require "bundler/setup"
+require "model_context_protocol"
+
+# You can add fixtures and/or initialization code here to make experimenting
+# with your gem easier. You can also use a different console, if you like.
+
+# (If you use this, don't forget to add pry to your Gemfile!)
+# require "pry"
+# Pry.start
+
+require "irb"
+IRB.start(__FILE__)

bin/rake

@@ -0,0 +1,31 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+#
+# This file was generated by Bundler.
+#
+# The application 'rake' is installed as part of a gem, and
+# this file is here to facilitate running it.
+#
+
+require "pathname"
+ENV["BUNDLE_GEMFILE"] ||= File.expand_path(
+  "../../Gemfile",
+  Pathname.new(__FILE__).realpath,
+)
+
+bundle_binstub = File.expand_path("../bundle", __FILE__)
+
+if File.file?(bundle_binstub)
+  if File.read(bundle_binstub, 300) =~ /This file was generated by Bundler/
+    load(bundle_binstub)
+  else
+    abort("Your `bin/bundle` was not generated by Bundler, so this binstub cannot run.
+Replace `bin/bundle` by running `bundle binstubs bundler --force`, then run this command again.")
+  end
+end
+
+require "rubygems"
+require "bundler/setup"
+
+load Gem.bin_path("rake", "rake")

bin/setup

@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+set -euo pipefail
+IFS=$'\n\t'
+set -vx
+
+bundle install
+
+# Do any other automated setup that you need to do here

dev.yml

@@ -0,0 +1,31 @@
+name: mcp-ruby
+
+type: ruby
+
+up:
+  - ruby
+  - bundler
+
+commands:
+  console:
+    desc: Open console with the gem loaded
+    run: bin/console
+  build:
+    desc: Build the gem using rake build
+    run: bin/rake build
+  test:
+    desc: Run tests
+    syntax:
+      argument: file
+      optional: args...
+    run:  |
+      if [[ $# -eq 0 ]]; then
+        bin/rake test
+      else
+        bin/rake -I test "$@"
+      fi
+  style:
+    desc: Run rubocop
+    aliases: [rubocop, lint]
+    run: bin/rubocop
+

lib/model_context_protocol.rb

@@ -0,0 +1,20 @@
+# typed: strict
+# frozen_string_literal: true
+
+require "model_context_protocol/json_rpc"
+require "model_context_protocol/server"
+require "model_context_protocol/tool"
+require "model_context_protocol/content"
+require "model_context_protocol/resource"
+require "model_context_protocol/prompt"
+
+module ModelContextProtocol
+  class Annotations
+    attr_reader :audience, :priority
+
+    def initialize(audience: nil, priority: nil)
+      @audience = audience
+      @priority = priority
+    end
+  end
+end

lib/model_context_protocol/content.rb

@@ -0,0 +1,33 @@
+# typed: true
+# frozen_string_literal: true
+
+module ModelContextProtocol
+  module Content
+    class Text
+      attr_reader :text, :annotations
+
+      def initialize(text, annotations: nil)
+        @text = text
+        @annotations = annotations
+      end
+
+      def to_h
+        { text:, annotations: }.compact
+      end
+    end
+
+    class Image
+      attr_reader :data, :mime_type, :annotations
+
+      def initialize(data, mime_type, annotations: nil)
+        @data = data
+        @mime_type = mime_type
+        @annotations = annotations
+      end
+
+      def to_h
+        { data:, mime_type:, annotations: }.compact
+      end
+    end
+  end
+end

lib/model_context_protocol/json_rpc.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+require "model_context_protocol/json_rpc/error"
+require "model_context_protocol/json_rpc/request"
+require "model_context_protocol/json_rpc/response"
+
+module ModelContextProtocol
+  module JsonRPC
+    VERSION = "2.0"
+  end
+end

lib/model_context_protocol/json_rpc/error.rb

@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+module ModelContextProtocol
+  module JsonRPC
+    class Error < StandardError
+      PARSE_ERROR_CODE     = -32700
+      INVALID_REQUEST_CODE = -32600
+      METHOD_NOT_FOUND_CODE = -32601
+      INVALID_PARAMS_CODE  = -32602
+      INTERNAL_ERROR_CODE  = -32603
+
+      attr_reader :code, :message, :data
+
+      def initialize(code:, message:, data: nil)
+        super(message)
+        @code = code
+        @message = message
+        @data = data
+      end
+
+      def to_h
+        { code:, message:, data: }.compact
+      end
+    end
+
+    class InvalidRequestError < Error
+      def initialize(message:)
+        super(code: INVALID_REQUEST_CODE, message: message)
+      end
+    end
+
+    class ParseError < Error
+      def initialize(message:)
+        super(code: PARSE_ERROR_CODE, message: message)
+      end
+    end
+
+    class MethodNotFoundError < Error
+      def initialize(message:)
+        super(code: METHOD_NOT_FOUND_CODE, message: message)
+      end
+    end
+
+    class InvalidParamsError < Error
+      def initialize(message:)
+        super(code: INVALID_PARAMS_CODE, message: message)
+      end
+    end
+
+    class InternalError < Error
+      def initialize(message:)
+        super(code: INTERNAL_ERROR_CODE, message: message)
+      end
+    end
+
+    class InvalidResponse < StandardError; end
+  end
+end

lib/model_context_protocol/json_rpc/request.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+require "json"
+
+module ModelContextProtocol
+  module JsonRPC
+    class Request
+      class << self
+        def parse(json)
+          parsed = JSON.parse(json)
+          from_h(parsed)
+        rescue JSON::ParserError => e
+          raise ParseError.new(message: e.message)
+        end
+
+        private
+
+        def from_h(hash)
+          new(version: hash["jsonrpc"], method: hash["method"], params: hash["params"], id: hash["id"])
+        end
+      end
+
+      attr_reader :version, :method, :params, :id
+
+      def initialize(version:, method:, params: nil, id: nil)
+        @version = version
+        @method = method
+        @params = params
+        @id = id
+      end
+
+      def notification?
+        id.nil?
+      end
+
+      def valid?
+        @version == JsonRPC::VERSION && !method.start_with?("rpc.")
+      end
+
+      def method_not_found!
+        raise MethodNotFoundError.new(message: "Method not found #{method}")
+      end
+
+      def validate!
+        raise InvalidRequestError.new(message: "Method cannot start with 'rpc.'") if method.start_with?("rpc.")
+        raise InvalidRequestError.new(message: "Invalid JSON-RPC version") unless valid?
+      end
+    end
+  end
+end