Add title to serverInfo

Follow-up to #109.

`title` has also been added to `serverInfo` and `clientInfo` by
https://github.com/modelcontextprotocol/modelcontextprotocol/pull/663.

Since `clientInfo` is not treated as product code, support is implemented only in `serverInfo`.

See also https://modelcontextprotocol.io/specification/2025-06-18/schema#implementation.

README.md

@@ -158,6 +158,7 @@ class ApplicationController < ActionController::Base
   def index
     server = MCP::Server.new(
       name: "my_server",
+      title: "Example Server Display Name", # WARNING: This is a `Draft` and is not supported in the `Version 2025-06-18 (latest)` specification.
       version: "1.0.0",
       instructions: "Use the tools of this server as a last resort",
       tools: [SomeTool, AnotherTool],

lib/mcp/server.rb

@@ -31,10 +31,11 @@ module MCP
 
     include Instrumentation
 
-    attr_accessor :name, :version, :instructions, :tools, :prompts, :resources, :server_context, :configuration, :capabilities, :transport
+    attr_accessor :name, :title, :version, :instructions, :tools, :prompts, :resources, :server_context, :configuration, :capabilities, :transport
 
     def initialize(
       name: "model_context_protocol",
+      title: nil,
       version: DEFAULT_VERSION,
       instructions: nil,
       tools: [],
@@ -47,6 +48,7 @@ module MCP
       transport: nil
     )
       @name = name
+      @title = title
       @version = version
       @instructions = instructions
       @tools = tools.to_h { |t| [t.name_value, t] }
@@ -218,6 +220,7 @@ module MCP
     def server_info
       @server_info ||= {
         name:,
+        title:,
         version:,
       }
     end

test/mcp/server_test.rb

@@ -69,6 +69,7 @@ module MCP
 
       @server = Server.new(
         name: @server_name,
+        title: "Example Server Display Name",
         version: "1.2.3",
         instructions: "Optional instructions for the client",
         tools: [@tool, @tool_that_raises],
@@ -140,6 +141,7 @@ module MCP
           },
           serverInfo: {
             name: @server_name,
+            title: "Example Server Display Name",
             version: "1.2.3",
           },
           instructions: "Optional instructions for the client",
@@ -769,6 +771,18 @@ module MCP
       assert_equal Configuration::DEFAULT_PROTOCOL_VERSION, response[:result][:protocolVersion]
     end
 
+    test "server uses default title when not configured" do
+      server = Server.new(name: "test_server")
+      request = {
+        jsonrpc: "2.0",
+        method: "initialize",
+        id: 1,
+      }
+
+      response = server.handle(request)
+      assert_nil response[:result][:serverInfo][:title]
+    end
+
     test "server uses default version when not configured" do
       server = Server.new(name: "test_server")
       request = {