Internal Release 0.2.0

- fix `lib/mcp-ruby` auto-import path
- implement server resources
- add basic listing of resources to Server
- allow setting handlers on Server
- wrap handler method results
- make tool definition more declarative
- make prompt definition more declarative
- bump dependency versions

.rubocop.yml

@@ -1,2 +1,5 @@
 inherit_gem:
   rubocop-shopify: rubocop.yml
+Naming/FileName:
+  Exclude:
+    - 'lib/mcp-ruby.rb'

Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    model_context_protocol (0.1.1)
+    model_context_protocol (0.2.2)
       activesupport
 
 GEM

README.md

@@ -59,43 +59,117 @@ end
 
 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.
+This gem provides a `ModelContextProtocol::Tool` class that can be used to create tools in two ways:
-
-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:
 
+1. As a class definition:
 ```ruby
-tool = ModelContextProtocol::Tool.new(name: "my_tool", description: "This tool performs specific functionality...") do |args|
+class MyTool < ModelContextProtocol::Tool
-  # Implement the tool's functionality here
+  tool_name "my_tool"
-  result = process_something(args["parameter_name"])
+  tool_description "This tool performs specific functionality..."
-  ModelContextProtocol::Tool::Response.new([{ type: "text", text: result }], false )
+  tool_input_schema [{ type: "text", name: "message" }]
+
+  def call(message)
+    Tool::Response.new([{ type: "text", content: "OK" }])
+  end
+end
+
+tool = MyTool.new
+```
+
+2. By using the `ModelContextProtocol::Tool.define` method with a block:
+```ruby
+tool = ModelContextProtocol::Tool.define(name: "my_tool", description: "This tool performs specific functionality...") do |args|
+  Tool::Response.new([{ type: "text", content: "OK" }])
 end
 ```
 
 ## Prompts
 
-MCP spec includes
+MCP spec includes [Prompts](https://modelcontextprotocol.io/docs/concepts/prompts), which enable servers to define reusable prompt templates and workflows that clients can easily surface to users and LLMs.
-[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.
+The `ModelContextProtocol::Prompt` class provides two ways to create prompts:
-
-To create a prompt, instantiate the class with the required parameters and an optional block:
 
+1. As a class definition with metadata:
 ```ruby
-prompt = ModelContextProtocol::Prompt.new(name: "my_prompt", description: "This prompt performs specific functionality...") do |args|
+class MyPrompt < ModelContextProtocol::Prompt
-  # Implement the prompt's functionality here
+  prompt_name "my_prompt"  # Optional - defaults to underscored class name
-  result = template_something(args["parameter_name"])
+  description "This prompt performs specific functionality..."
-  ModelContextProtocol::Prompt::Response.new([{ type: "text", text: result }], false )
+  arguments [
+    Prompt::Argument.new(
+      name: "message",
+      description: "Input message",
+      required: true
+    )
+  ]
+
+  def template(args)
+    Prompt::Result.new(
+      description: "Response description",
+      messages: [
+        Prompt::Message.new(
+          role: "user",
+          content: Content::Text.new("User message")
+        ),
+        Prompt::Message.new(
+          role: "assistant",
+          content: Content::Text.new(args["message"])
+        )
+      ]
+    )
+  end
 end
 ```
 
+2. Using the `ModelContextProtocol::Prompt.define` method:
+```ruby
+prompt = ModelContextProtocol::Prompt.define(
+  name: "my_prompt",
+  description: "This prompt performs specific functionality...",
+  arguments: [
+    Prompt::Argument.new(
+      name: "message",
+      description: "Input message",
+      required: true
+    )
+  ]
+) do |args|
+  Prompt::Result.new(
+    description: "Response description",
+    messages: [
+      Prompt::Message.new(
+        role: "user",
+        content: Content::Text.new("User message")
+      ),
+      Prompt::Message.new(
+        role: "assistant",
+        content: Content::Text.new(args["message"])
+      )
+    ]
+  )
+end
+```
 
+### Key Components
 
+- `Prompt::Argument` - Defines input parameters for the prompt template
+- `Prompt::Message` - Represents a message in the conversation with a role and content
+- `Prompt::Result` - The output of a prompt template containing description and messages
+- `Content::Text` - Text content for messages
+
+### Usage
+
+Register prompts with the MCP server:
+
+```ruby
+server = ModelContextProtocol::Server.new(
+  name: "my_server",
+  prompts: [MyPrompt.new]
+)
+```
+
+The server will handle prompt listing and execution through the MCP protocol methods:
+- `prompts/list` - Lists all registered prompts and their schemas
+- `prompts/get` - Retrieves and executes a specific prompt with arguments
 
 ## Releases
 

lib/mcp-ruby.rb

@@ -0,0 +1,3 @@
+# frozen_string_literal: true
+
+require "model_context_protocol"

lib/model_context_protocol.rb

@@ -7,6 +7,7 @@ require "model_context_protocol/tool"
 require "model_context_protocol/content"
 require "model_context_protocol/resource"
 require "model_context_protocol/prompt"
+require "model_context_protocol/version"
 
 module ModelContextProtocol
   class Annotations

lib/model_context_protocol/prompt.rb

@@ -44,19 +44,59 @@ module ModelContextProtocol
       end
     end
 
+    class << self
+      attr_reader :description_value
+      attr_reader :arguments_value
+
+      def inherited(subclass)
+        super
+        subclass.instance_variable_set(:@name_value, nil)
+        subclass.instance_variable_set(:@description_value, nil)
+        subclass.instance_variable_set(:@arguments_value, nil)
+      end
+
+      def prompt_name(value)
+        @name_value = value
+      end
+
+      def name_value
+        @name_value || name.demodulize.underscore
+      end
+
+      def description(value)
+        @description_value = value
+      end
+
+      def arguments(value)
+        @arguments_value = value
+      end
+
+      def define(name: nil, description: nil, arguments: [], &block)
+        new(name:, description:, arguments:).tap do |prompt|
+          prompt.define_singleton_method(:template) do |args|
+            instance_exec(args, &block)
+          end
+        end
+      end
+    end
+
     attr_reader :name, :description, :arguments
 
-    def initialize(name:, description: nil, arguments: [], &block)
+    def initialize(name: nil, description: nil, arguments: nil)
-      @name = name
+      @name = name || self.class.name_value
-      @description = description
+      @description = description || self.class.description_value
-      @arguments = arguments
+      @arguments = arguments || self.class.arguments_value
-      @template_block = block
     end
 
     def template(args)
-      validate_args!(args)
+      raise NotImplementedError, "Prompt subclasses must implement template"
-      result = @template_block.call(args)
+    end
-      result
+
+    def validate_arguments!(args)
+      missing = required_args - args.keys
+      return if missing.empty?
+
+      raise ArgumentError, "Missing required arguments: #{missing.join(", ")}"
     end
 
     def to_h
@@ -68,12 +108,5 @@ module ModelContextProtocol
     def required_args
       arguments.filter_map { |arg| arg.name if arg.required }
     end
-
-    def validate_args!(args)
-      missing = required_args - args.keys
-      return if missing.empty?
-
-      raise ArgumentError, "Missing required arguments: #{missing.join(", ")}"
-    end
   end
 end

lib/model_context_protocol/resource.rb

@@ -2,57 +2,25 @@
 # frozen_string_literal: true
 
 module ModelContextProtocol
-  module Resource
+  class Resource
-    class Embedded
+    attr_reader :uri, :name, :description, :mime_type, :contents
-      attr_reader :resource, :annotations
 
-      def initialize(resource:, annotations: nil)
+    def initialize(uri:, name:, description:, mime_type:, contents:)
-        @resource = resource
+      @uri = uri
-        @annotations = annotations
+      @name = name
-      end
+      @description = description
-
+      @mime_type = mime_type
-      def to_h
+      @contents = contents
-        { resource: resource.to_h, annotations: }.compact
-      end
     end
 
-    class Contents
+    def to_h
-      attr_reader :uri, :mime_type
+      {
-
+        uri: @uri,
-      def initialize(uri:, mime_type: nil)
+        name: @name,
-        @uri = uri
+        description: @description,
-        @mime_type = mime_type
+        mimeType: @mime_type,
-      end
+        contents: @contents.map(&:to_h),
-
+      }
-      def to_h
-        { uri:, mime_type: }.compact
-      end
-    end
-
-    class TextContents < Contents
-      attr_reader :text
-
-      def initialize(text:, uri:, mime_type:)
-        super(uri: uri, mime_type: mime_type)
-        @text = text
-      end
-
-      def to_h
-        super.merge(text: text)
-      end
-    end
-
-    class BlobContents < Contents
-      attr_reader :data
-
-      def initialize(data:, uri:, mime_type:)
-        super(uri: uri, mime_type: mime_type)
-        @data = data
-      end
-
-      def to_h
-        super.merge(data: data)
-      end
     end
   end
 end

lib/model_context_protocol/resource/contents.rb

@@ -0,0 +1,45 @@
+# typed: strict
+# frozen_string_literal: true
+
+module ModelContextProtocol
+  class Resource
+    class Contents
+      attr_reader :uri, :mime_type
+
+      def initialize(uri:, mime_type: nil)
+        @uri = uri
+        @mime_type = mime_type
+      end
+
+      def to_h
+        { uri:, mime_type: }.compact
+      end
+    end
+
+    class TextContents < Contents
+      attr_reader :text
+
+      def initialize(text:, uri:, mime_type:)
+        super(uri: uri, mime_type: mime_type)
+        @text = text
+      end
+
+      def to_h
+        super.merge(text: text)
+      end
+    end
+
+    class BlobContents < Contents
+      attr_reader :data
+
+      def initialize(data:, uri:, mime_type:)
+        super(uri: uri, mime_type: mime_type)
+        @data = data
+      end
+
+      def to_h
+        super.merge(data: data)
+      end
+    end
+  end
+end

lib/model_context_protocol/resource/embedded.rb

@@ -0,0 +1,18 @@
+# typed: strict
+# frozen_string_literal: true
+
+module ModelContextProtocol
+  class Resource
+    class Embedded
+      attr_reader :resource, :annotations
+
+      def initialize(resource:, annotations: nil)
+        @annotations = annotations
+      end
+
+      def to_h
+        { resource: resource.to_h, annotations: }.compact
+      end
+    end
+  end
+end

lib/model_context_protocol/server.rb

@@ -4,12 +4,25 @@ module ModelContextProtocol
   class Server
     PROTOCOL_VERSION = "2024-11-05"
 
-    attr_accessor :name, :tools, :prompts
+    attr_accessor :name, :tools, :prompts, :resources
 
-    def initialize(name: "model_context_protocol", tools: [], prompts: [])
+    def initialize(name: "model_context_protocol", tools: [], prompts: [], resources: [])
       @name = name
       @tools = tools.to_h { |t| [t.name, t] }
       @prompts = prompts.to_h { |p| [p.name, p] }
+      @resources = resources
+      @resource_index = resources.index_by(&:uri)
+
+      @handlers = {
+        "resources/list" => method(:list_resources),
+        "resources/read" => method(:read_resource),
+        "tools/list" => method(:list_tools),
+        "tools/call" => method(:call_tool),
+        "prompts/list" => method(:list_prompts),
+        "prompts/get" => method(:get_prompt),
+        "initialize" => method(:init),
+        "ping" => method(:ping),
+      }
     end
 
     def handle(request)
@@ -20,7 +33,7 @@ module ModelContextProtocol
         if parsed_request.notification?
           handle_notification(parsed_request)
         else
-          call_method(parsed_request)
+          handle_method(parsed_request)
         end
       rescue JsonRPC::Error => e
         JsonRPC::Response.new(id: parsed_request&.id, error: e)
@@ -29,35 +42,32 @@ module ModelContextProtocol
       response
     end
 
+    def resources_list_handler(&block)
+      @handlers["resources/list"] = block
+    end
+
+    def resources_read_handler(&block)
+      @handlers["resources/read"] = block
+    end
+
+    def tools_list_handler(&block)
+      @handlers["tools/list"] = block
+    end
+
+    def tools_call_handler(&block)
+      @handlers["tools/call"] = block
+    end
+
+    def prompts_list_handler(&block)
+      @handlers["prompts/list"] = block
+    end
+
+    def prompts_get_handler(&block)
+      @handlers["prompts/get"] = block
+    end
+
     private
 
-    def handle_notification(request)
-      nil
-    end
-
-    def call_method(request)
-      case request.method
-      when "initialize"
-        JsonRPC::Response.new(id: request.id, result: {
-          protocolVersion: PROTOCOL_VERSION,
-          capabilities: capabilities,
-          serverInfo: server_info,
-        })
-      when "ping"
-        JsonRPC::Response.new(id: request.id, result: "pong")
-      when "tools/list"
-        list_tools(request)
-      when "tools/call"
-        call_tool(request)
-      when "prompts/list"
-        list_prompts(request)
-      when "prompts/get"
-        get_prompt(request)
-      else
-        raise JsonRPC::MethodNotFoundError.new(message: "Method not found #{request.method}")
-      end
-    end
-
     def capabilities
       @capabilities ||= {
         experimental: nil,
@@ -76,6 +86,41 @@ module ModelContextProtocol
       }
     end
 
+    def handle_notification(request)
+      nil
+    end
+
+    def handle_method(request)
+      request_handler = @handlers[request.method]
+      raise JsonRPC::MethodNotFoundError.new(message: "Method not found #{request.method}") unless request_handler
+
+      result = request_handler.call(request)
+      wrapped_result = case request.method
+      when "tools/list"
+        { tools: result }
+      when "prompts/list"
+        { prompts: result }
+      when "resources/list"
+        { resources: result }
+      else
+        result
+      end
+
+      JsonRPC::Response.new(id: request.id, result: wrapped_result)
+    end
+
+    def init(request)
+      {
+        protocolVersion: PROTOCOL_VERSION,
+        capabilities: capabilities,
+        serverInfo: server_info,
+      }
+    end
+
+    def ping(request)
+      "pong"
+    end
+
     def call_tool(request)
       tool_name = request.params&.dig("name")
       tool = tools[tool_name]
@@ -89,15 +134,15 @@ module ModelContextProtocol
         raise JsonRPC::InternalError.new(message: e.message)
       end
 
-      JsonRPC::Response.new(id: request.id, result: result.to_h)
+      result.to_h
     end
 
     def list_tools(request)
-      JsonRPC::Response.new(id: request.id, result: { tools: @tools.map { |_, tool| tool.to_h } })
+      @tools.map { |_, tool| tool.to_h }
     end
 
     def list_prompts(request)
-      JsonRPC::Response.new(id: request.id, result: { prompts: @prompts.map { |_, prompt| prompt.to_h } })
+      @prompts.map { |_, prompt| prompt.to_h }
     end
 
     def get_prompt(request)
@@ -106,12 +151,28 @@ module ModelContextProtocol
       raise JsonRPC::MethodNotFoundError.new(message: "Prompt not found #{prompt_name}") unless prompt
 
       begin
-        result = prompt.template(request.params&.dig("arguments") || {})
+        prompt_args = request.params&.dig("arguments")
+        prompt.validate_arguments!(prompt_args)
+
+        result = prompt.template(prompt_args)
       rescue ArgumentError => e
         raise JsonRPC::InvalidParamsError.new(message: e.message)
       end
 
-      JsonRPC::Response.new(id: request.id, result: result.to_h)
+      result.to_h
+    end
+
+    def list_resources(request)
+      @resources.map(&:to_h)
+    end
+
+    def read_resource(request)
+      resource_uri = request.params&.dig("uri")
+
+      resource = @resource_index[resource_uri]
+      raise JsonRPC::MethodNotFoundError.new(message: "Resource not found #{resource_uri}") unless resource
+
+      resource.to_h
     end
   end
 end

lib/model_context_protocol/tool.rb

@@ -15,17 +15,52 @@ module ModelContextProtocol
       end
     end
 
+    class << self
+      attr_reader :description_value
+      attr_reader :input_schema_value
+
+      def inherited(subclass)
+        super
+        subclass.instance_variable_set(:@name_value, nil)
+        subclass.instance_variable_set(:@description_value, nil)
+        subclass.instance_variable_set(:@input_schema_value, nil)
+      end
+
+      def tool_name(value)
+        @name_value = value
+      end
+
+      def name_value
+        @name_value || name.demodulize.underscore
+      end
+
+      def description(value)
+        @description_value = value
+      end
+
+      def input_schema(value)
+        @input_schema_value = value
+      end
+
+      def define(name: nil, description: nil, input_schema: nil, &block)
+        new(name:, description:, input_schema:).tap do |tool|
+          tool.define_singleton_method(:call) do |*args|
+            instance_exec(*args, &block)
+          end
+        end
+      end
+    end
+
     attr_reader :name, :description, :input_schema
 
-    def initialize(name:, description: nil, input_schema: nil, &block)
+    def initialize(name: nil, description: nil, input_schema: nil)
-      @name = name
+      @name = name || self.class.name_value
-      @description = description
+      @description = description || self.class.description_value
-      @input_schema = input_schema
+      @input_schema = input_schema || self.class.input_schema_value
-      @tool_block = block_given? ? block : -> { Response.new([{ type: "text", content: "OK" }]) }
     end
 
     def call(*args)
-      @tool_block.call(*args)
+      raise NotImplementedError, "Subclasses must implement call"
     end
 
     def to_h

lib/model_context_protocol/version.rb

@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module ModelContextProtocol
-  VERSION = "0.1.1"
+  VERSION = "0.2.2"
 end

test/model_context_protocol/prompt_test.rb

@@ -5,27 +5,13 @@ require "test_helper"
 
 module ModelContextProtocol
   class PromptTest < ActiveSupport::TestCase
-    test "#template validates arguments" do
+    class TestPrompt < Prompt
-      prompt = Prompt.new(
+      description "Test prompt"
-        name: "test_prompt",
+      arguments [
-        description: "Test prompt",
+        Prompt::Argument.new(name: "test_argument", description: "Test argument", required: true),
-        arguments: [
+      ]
-          Prompt::Argument.new(name: "test_argument", description: "Test argument", required: true),
-        ],
-      )
-      assert_raises(ArgumentError) do
-        prompt.template({})
-      end
-    end
 
-    test "#template returns a Result with description and messages when arguments are valid" do
+      def template(args)
-      prompt = Prompt.new(
-        name: "test_prompt",
-        description: "Test prompt",
-        arguments: [
-          Prompt::Argument.new(name: "test_argument", description: "Test argument", required: true),
-        ],
-      ) do |_|
         Prompt::Result.new(
           description: "Hello, world!",
           messages: [
@@ -34,6 +20,108 @@ module ModelContextProtocol
           ],
         )
       end
+    end
+
+    test "#template returns a Result with description and messages" do
+      prompt = TestPrompt.new
+
+      expected_template_result = {
+        description: "Hello, world!",
+        messages: [
+          { role: "user", content: { text: "Hello, world!" } },
+          { role: "assistant", content: { text: "Hello, friend!" } },
+        ],
+      }
+
+      result = prompt.template({ "test_argument" => "Hello, friend!" })
+
+      assert_equal expected_template_result, result.to_h
+    end
+
+    test "allows declarative definition of prompts as classes" do
+      class MockPrompt < Prompt
+        prompt_name "my_mock_prompt"
+        description "a mock prompt for testing"
+        arguments [
+          Prompt::Argument.new(name: "test_argument", description: "Test argument", required: true),
+        ]
+
+        def template(args)
+          Prompt::Result.new(
+            description: "Hello, world!",
+            messages: [
+              Prompt::Message.new(role: "user", content: Content::Text.new("Hello, world!")),
+              Prompt::Message.new(role: "assistant", content: Content::Text.new(args["test_argument"])),
+            ],
+          )
+        end
+      end
+
+      prompt = MockPrompt.new
+
+      assert_equal "my_mock_prompt", prompt.name
+      assert_equal "a mock prompt for testing", prompt.description
+      assert_equal "test_argument", prompt.arguments.first.name
+      assert_equal "Test argument", prompt.arguments.first.description
+      assert_equal true, prompt.arguments.first.required
+
+      expected_template_result = {
+        description: "Hello, world!",
+        messages: [
+          { role: "user", content: { text: "Hello, world!" } },
+          { role: "assistant", content: { text: "Hello, friend!" } },
+        ],
+      }
+
+      result = prompt.template({ "test_argument" => "Hello, friend!" })
+      assert_equal expected_template_result, result.to_h
+    end
+
+    test "defaults to class name as prompt name" do
+      class DefaultNamePrompt < Prompt
+        description "a mock prompt for testing"
+        arguments [
+          Prompt::Argument.new(name: "test_argument", description: "Test argument", required: true),
+        ]
+
+        def template(args)
+          Prompt::Result.new(
+            description: "Hello, world!",
+            messages: [
+              Prompt::Message.new(role: "user", content: Content::Text.new("Hello, world!")),
+              Prompt::Message.new(role: "assistant", content: Content::Text.new(args["test_argument"])),
+            ],
+          )
+        end
+      end
+
+      prompt = DefaultNamePrompt.new
+
+      assert_equal "default_name_prompt", prompt.name
+      assert_equal "a mock prompt for testing", prompt.description
+      assert_equal "test_argument", prompt.arguments.first.name
+    end
+
+    test ".define allows definition of simple prompts with a block" do
+      prompt = Prompt.define(
+        name: "mock_prompt",
+        description: "a mock prompt for testing",
+        arguments: [
+          Prompt::Argument.new(name: "test_argument", description: "Test argument", required: true),
+        ],
+      ) do |args|
+        Prompt::Result.new(
+          description: "Hello, world!",
+          messages: [
+            Prompt::Message.new(role: "user", content: Content::Text.new("Hello, world!")),
+            Prompt::Message.new(role: "assistant", content: Content::Text.new(args["test_argument"])),
+          ],
+        )
+      end
+
+      assert_equal "mock_prompt", prompt.name
+      assert_equal "a mock prompt for testing", prompt.description
+      assert_equal "test_argument", prompt.arguments.first.name
 
       expected = {
         description: "Hello, world!",
@@ -44,7 +132,6 @@ module ModelContextProtocol
       }
 
       result = prompt.template({ "test_argument" => "Hello, friend!" })
-
       assert_equal expected, result.to_h
     end
   end

test/model_context_protocol/server_test.rb

@@ -7,7 +7,7 @@ module ModelContextProtocol
     setup do
       @tool = Tool.new(name: "test_tool", description: "Test tool", input_schema: {})
 
-      @prompt = Prompt.new(
+      @prompt = Prompt.define(
         name: "test_prompt",
         description: "Test prompt",
         arguments: [
@@ -22,11 +22,19 @@ module ModelContextProtocol
         )
       end
 
+      @resource = Resource.new(
+        uri: "test_resource",
+        name: "Test resource",
+        description: "Test resource",
+        mime_type: "text/plain",
+        contents: [Content::Text.new("Hello, world!")],
+      )
+
       @server_name = "test_server"
-      @server = Server.new(name: @server_name, tools: [@tool], prompts: [@prompt])
+      @server = Server.new(name: @server_name, tools: [@tool], prompts: [@prompt], resources: [@resource])
     end
 
-    test "ping request returns pong" do
+    test "#handle ping request returns pong" do
       request = {
         jsonrpc: "2.0",
         method: "ping",
@@ -40,7 +48,7 @@ module ModelContextProtocol
       assert_equal 1, response.id
     end
 
-    test "initialize request returns protocol info, server info, and capabilities" do
+    test "#handle initialize request returns protocol info, server info, and capabilities" do
       request = {
         jsonrpc: "2.0",
         method: "initialize",
@@ -58,7 +66,22 @@ module ModelContextProtocol
       assert_equal ModelContextProtocol::VERSION, result[:serverInfo][:version]
     end
 
-    test "tools/list returns available tools" do
+    test "#handle returns nil for notification requests" do
+      request = {
+        jsonrpc: "2.0",
+        method: "some_notification",
+      }.to_json
+
+      assert_nil @server.handle(request)
+    end
+
+    test "#handle returns error response for invalid requests" do
+      response = @server.handle("invalid json")
+      assert_instance_of JsonRPC::Response, response
+      assert_instance_of(JsonRPC::ParseError, response.error)
+    end
+
+    test "#handle tools/list returns available tools" do
       request = {
         jsonrpc: "2.0",
         method: "tools/list",
@@ -72,16 +95,22 @@ module ModelContextProtocol
       assert_equal({}, response.result[:tools][0][:inputSchema])
     end
 
-    test "returns nil for notification requests" do
+    test "#tools_list_handler sets the tools/list handler" do
+      @server.tools_list_handler do
+        [{ name: "hammer", description: "Hammer time!" }]
+      end
+
       request = {
         jsonrpc: "2.0",
-        method: "some_notification",
+        method: "tools/list",
+        id: 1,
       }.to_json
 
-      assert_nil @server.handle(request)
+      response = @server.handle(request)
+      assert_equal({ tools: [{ name: "hammer", description: "Hammer time!" }] }, response.result)
     end
 
-    test "tools/call executes tool and returns result" do
+    test "#handle tools/call executes tool and returns result" do
       tool_name = "test_tool"
       tool_args = { "arg" => "value" }
       tool_response = Tool::Response.new([{ "result" => "success" }])
@@ -102,7 +131,7 @@ module ModelContextProtocol
       assert_equal tool_response.to_h, response.result
     end
 
-    test "tools/call returns error if the tool raises an error" do
+    test "#handle tools/call returns error if the tool raises an error" do
       @tool.expects(:call).raises(StandardError.new("Tool error"))
 
       request = {
@@ -121,13 +150,7 @@ module ModelContextProtocol
       assert_equal "Tool error", response.error&.message
     end
 
-    test "returns error response for invalid requests" do
+    test "#handle tools/call returns error for unknown tool" do
-      response = @server.handle("invalid json")
-      assert_instance_of JsonRPC::Response, response
-      assert_instance_of(JsonRPC::ParseError, response.error)
-    end
-
-    test "tools/call returns error for unknown tool" do
       request = {
         jsonrpc: "2.0",
         method: "tools/call",
@@ -143,7 +166,24 @@ module ModelContextProtocol
       assert_instance_of(JsonRPC::MethodNotFoundError, response.error)
     end
 
-    test "prompts/list returns list of prompts" do
+    test "#tools_call_handler sets the tools/call handler" do
+      @server.tools_call_handler do |request|
+        tool_name = request.params&.dig("name")
+        return Tool::Response.new("#{tool_name} called successfully").to_h
+      end
+
+      request = {
+        jsonrpc: "2.0",
+        method: "tools/call",
+        params: { name: "my_tool", arguments: {} },
+        id: 1,
+      }.to_json
+
+      response = @server.handle(request)
+      assert_equal({ content: "my_tool called successfully", is_error: false }, response.result)
+    end
+
+    test "#handle prompts/list returns list of prompts" do
       request = {
         jsonrpc: "2.0",
         method: "prompts/list",
@@ -154,7 +194,22 @@ module ModelContextProtocol
       assert_equal({ prompts: [@prompt.to_h] }, response.result)
     end
 
-    test "prompts/get returns templated prompt" do
+    test "#prompts_list_handler sets the prompts/list handler" do
+      @server.prompts_list_handler do
+        [{ name: "foo_prompt", description: "Foo prompt" }]
+      end
+
+      request = {
+        jsonrpc: "2.0",
+        method: "prompts/list",
+        id: 1,
+      }.to_json
+
+      response = @server.handle(request)
+      assert_equal({ prompts: [{ name: "foo_prompt", description: "Foo prompt" }] }, response.result)
+    end
+
+    test "#handle prompts/get returns templated prompt" do
       request = {
         jsonrpc: "2.0",
         method: "prompts/get",
@@ -177,7 +232,7 @@ module ModelContextProtocol
       assert_equal(expected_result, response.result)
     end
 
-    test "prompts/get returns error if prompt is not found" do
+    test "#handle prompts/get returns error if prompt is not found" do
       request = {
         jsonrpc: "2.0",
         method: "prompts/get",
@@ -193,7 +248,7 @@ module ModelContextProtocol
       assert_instance_of(JsonRPC::MethodNotFoundError, response.error)
     end
 
-    test "prompts/get returns error if prompt arguments are invalid" do
+    test "#handle prompts/get returns error if prompt arguments are invalid" do
       request = {
         jsonrpc: "2.0",
         method: "prompts/get",
@@ -210,11 +265,129 @@ module ModelContextProtocol
       assert_equal "Missing required arguments: test_argument", response.error.message
     end
 
-    test "unknown method returns method not found error" do
+    test "#prompts_get_handler sets the prompts/get handler" do
+      @server.prompts_get_handler do |request|
+        prompt_name = request.params&.dig("name")
+        return Prompt::Result.new(
+          description: prompt_name,
+          messages: [
+            Prompt::Message.new(role: "user", content: Content::Text.new(request.params&.dig("arguments", "foo"))),
+          ],
+        ).to_h
+      end
+
       request = {
         jsonrpc: "2.0",
-        method: "unknown_method",
+        method: "prompts/get",
         id: 1,
+        params: { name: "foo_bar_prompt", arguments: { "foo" => "bar" } },
+      }.to_json
+
+      response = @server.handle(request)
+      assert_equal(
+        { description: "foo_bar_prompt", messages: [{ role: "user", content: { text: "bar" } }] },
+        response.result,
+      )
+    end
+
+    test "#handle resources/list returns a list of resources" do
+      request = {
+        jsonrpc: "2.0",
+        method: "resources/list",
+        id: 1,
+      }.to_json
+
+      response = @server.handle(request)
+      assert_equal({ resources: [@resource.to_h] }, response.result)
+    end
+
+    test "#resources_list_handler sets the resources/list handler" do
+      @server.resources_list_handler do
+        [{ uri: "test_resource", name: "Test resource", description: "Test resource" }]
+      end
+
+      request = {
+        jsonrpc: "2.0",
+        method: "resources/list",
+        id: 1,
+      }.to_json
+
+      response = @server.handle(request)
+      assert_equal(
+        { resources: [{ uri: "test_resource", name: "Test resource", description: "Test resource" }] },
+        response.result,
+      )
+    end
+
+    test "#handle resources/read returns a resource" do
+      request = {
+        jsonrpc: "2.0",
+        method: "resources/read",
+        id: 1,
+        params: {
+          uri: @resource.uri,
+        },
+      }.to_json
+
+      response = @server.handle(request)
+      assert_equal(@resource.to_h, response.result)
+    end
+
+    test "#handle resources/read returns error if resource is not found" do
+      request = {
+        jsonrpc: "2.0",
+        method: "resources/read",
+        id: 1,
+        params: {
+          uri: "unknown_resource",
+        },
+      }.to_json
+
+      response = @server.handle(request)
+      assert_instance_of(JsonRPC::Response, response)
+      assert_equal "Resource not found unknown_resource", response.error.message
+    end
+
+    test "#resources_read_handler sets the resources/read handler" do
+      @server.resources_read_handler do |request|
+        uri = request.params&.dig("uri")
+
+        Resource.new(
+          uri: uri,
+          name: "Test resource",
+          description: "Test resource",
+          mime_type: "text/plain",
+          contents: [Content::Text.new("Lorem ipsum dolor sit amet")],
+        ).to_h
+      end
+
+      request = {
+        jsonrpc: "2.0",
+        method: "resources/read",
+        id: 1,
+        params: {
+          uri: "test_resource",
+        },
+      }.to_json
+
+      response = @server.handle(request)
+      assert_equal(
+        {
+          uri: "test_resource",
+          name: "Test resource",
+          description: "Test resource",
+          mimeType: "text/plain",
+          contents: [{ text: "Lorem ipsum dolor sit amet" }],
+        },
+        response.result,
+      )
+    end
+
+    test "#handle unknown method returns method not found error" do
+      request = {
+        jsonrpc: "2.0",
+        id: 1,
+        method: "unknown_method",
       }.to_json
 
       response = @server.handle(request)

test/model_context_protocol/tool_test.rb

@@ -4,19 +4,62 @@ require "test_helper"
 
 module ModelContextProtocol
   class ToolTest < ActiveSupport::TestCase
+    class TestTool < Tool
+      tool_name "test_tool"
+      description "a test tool for testing"
+      input_schema [{ type: "text", name: "message" }]
+
+      def call(message)
+        Tool::Response.new([{ type: "text", content: "OK" }])
+      end
+    end
+
     test "#to_h returns a hash with name, description, and inputSchema" do
       tool = Tool.new(name: "mock_tool", description: "a mock tool for testing")
       assert_equal tool.to_h, { name: "mock_tool", description: "a mock tool for testing", inputSchema: nil }
     end
 
     test "#call invokes the tool block and returns the response" do
-      tool = Tool.new(name: "mock_tool", description: "a mock tool for testing") do |_|
+      tool = TestTool.new
-        Tool::Response.new([{ type: "text", content: "OK" }])
+      response = tool.call("test")
-      end
-
-      response = tool.call
       assert_equal response.content, [{ type: "text", content: "OK" }]
       assert_equal response.is_error, false
     end
+
+    test "allows declarative definition of tools as classes" do
+      class MockTool < Tool
+        tool_name "my_mock_tool"
+        description "a mock tool for testing"
+        input_schema [{ type: "text", name: "message" }]
+      end
+
+      tool = MockTool.new
+      assert_equal tool.name, "my_mock_tool"
+      assert_equal tool.description, "a mock tool for testing"
+      assert_equal tool.input_schema, [{ type: "text", name: "message" }]
+    end
+
+    test "defaults to class name as tool name" do
+      class DefaultNameTool < Tool
+        description "a mock tool for testing"
+        input_schema [{ type: "text", name: "message" }]
+      end
+
+      tool = DefaultNameTool.new
+
+      assert_equal tool.name, "default_name_tool"
+      assert_equal tool.description, "a mock tool for testing"
+      assert_equal tool.input_schema, [{ type: "text", name: "message" }]
+    end
+
+    test ".define allows definition of simple tools with a block" do
+      tool = Tool.define(name: "mock_tool", description: "a mock tool for testing") do |_|
+        Tool::Response.new([{ type: "text", content: "OK" }])
+      end
+
+      assert_equal tool.name, "mock_tool"
+      assert_equal tool.description, "a mock tool for testing"
+      assert_equal tool.input_schema, nil
+    end
   end
 end