add meta value to prompt

allow title on prompt arguments

Author: topherbullock

lib/mcp/prompt.rb

@@ -8,13 +8,20 @@ class << self
       attr_reader :title_value
       attr_reader :description_value
       attr_reader :arguments_value
+      attr_reader :meta_value
 
       def template(args, server_context: nil)
         raise NotImplementedError, "Subclasses must implement template"
       end
 
       def to_h
-        { name: name_value, title: title_value, description: description_value, arguments: arguments_value.map(&:to_h) }.compact
+        {
+          name: name_value,
+          title: title_value,
+          description: description_value,
+          arguments: arguments_value&.map(&:to_h),
+          _meta: meta_value,
+        }.compact
       end
 
       def inherited(subclass)
@@ -23,6 +30,7 @@ def inherited(subclass)
         subclass.instance_variable_set(:@title_value, nil)
         subclass.instance_variable_set(:@description_value, nil)
         subclass.instance_variable_set(:@arguments_value, nil)
+        subclass.instance_variable_set(:@meta_value, nil)
       end
 
       def prompt_name(value = NOT_SET)
@@ -61,7 +69,15 @@ def arguments(value = NOT_SET)
         end
       end
 
-      def define(name: nil, title: nil, description: nil, arguments: [], &block)
+      def meta(value = NOT_SET)
+        if value == NOT_SET
+          @meta_value
+        else
+          @meta_value = value
+        end
+      end
+
+      def define(name: nil, title: nil, description: nil, arguments: [], meta: nil, &block)
         Class.new(self) do
           prompt_name name
           title title
@@ -70,6 +86,7 @@ def define(name: nil, title: nil, description: nil, arguments: [], &block)
           define_singleton_method(:template) do |args, server_context: nil|
             instance_exec(args, server_context:, &block)
           end
+          meta meta
         end
       end
 

lib/mcp/prompt/argument.rb

@@ -3,17 +3,22 @@
 module MCP
   class Prompt
     class Argument
-      attr_reader :name, :description, :required, :arguments
+      attr_reader :name, :title, :description, :required
 
-      def initialize(name:, description: nil, required: false)
+      def initialize(name:, title: nil, description: nil, required: false)
         @name = name
+        @title = title
         @description = description
         @required = required
-        @arguments = arguments
       end
 
       def to_h
-        { name:, description:, required: }.compact
+        {
+          name: name,
+          title: title,
+          description: description,
+          required: required,
+        }.compact
       end
     end
   end

test/mcp/prompt_test.rb

@@ -113,8 +113,14 @@ def template(args, server_context:)
         title: "Mock Prompt",
         description: "a mock prompt for testing",
         arguments: [
-          Prompt::Argument.new(name: "test_argument", description: "Test argument", required: true),
+          Prompt::Argument.new(
+            name: "test_argument",
+            title: "Test argument title",
+            description: "This is a test argument description",
+            required: true,
+          ),
         ],
+        meta: { foo: "bar" },
       ) do |args, server_context:|
         content = Content::Text.new(args["test_argument"] + " user: #{server_context[:user_id]}")
 
@@ -130,6 +136,10 @@ def template(args, server_context:)
       assert_equal "mock_prompt", prompt.name_value
       assert_equal "a mock prompt for testing", prompt.description
       assert_equal "test_argument", prompt.arguments.first.name
+      assert_equal "Test argument title", prompt.arguments.first.title
+      assert_equal "This is a test argument description", prompt.arguments.first.description
+      assert prompt.arguments.first.required
+      assert_equal({ foo: "bar" }, prompt.meta_value)
 
       expected = {
         description: "Hello, world!",