[WIP] Test README tool definition examples

This revealed that the `define` example doesn't work, and the fix is
unclear.

Author: sambostock

README.md

@@ -284,6 +284,7 @@ This gem provides a `MCP::Tool` class that can be used to create tools in two wa
 
 1. As a class definition:
 
+<!-- SNIPPET ID: tool_class_definition -->
 ```ruby
 class MyTool < MCP::Tool
   description "This tool performs specific functionality..."
@@ -311,6 +312,7 @@ tool = MyTool
 
 2. By using the `MCP::Tool.define` method with a block:
 
+<!-- SNIPPET ID: tool_definition_with_block -->
 ```ruby
 tool = MCP::Tool.define(
   name: "my_tool",

test/fixtures/files/code_snippet_wrappers/readme/tool_class_definition.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+require "mcp"
+
+require_relative "code_snippet"
+
+b = binding
+eval(File.read("code_snippet.rb"), b) # rubocop:disable Security/Eval -- We need to run the snippet in this context to extract the tool
+tool = b.local_variable_get(:tool)
+
+MCP.configure do |config|
+  config.exception_reporter = ->(exception, server_context) do
+    $stderr.puts "Exception: #{exception.inspect}"
+    $stderr.puts "Exception cause: #{exception.cause.inspect}"
+  end
+end
+
+puts MCP::Server.new(tools: [tool]).handle_json(
+  {
+    jsonrpc: "2.0",
+    id: "1",
+    method: "tools/call",
+    params: { name: "my_tool", arguments: { message: "Hello, world!" } },
+  }.to_json,
+)

test/fixtures/files/code_snippet_wrappers/readme/tool_definition_with_block.rb

@@ -0,0 +1 @@
+tool_class_definition.rb

test/integration/readme_code_snippets_test.rb

@@ -137,6 +137,24 @@ class ReadmeCodeSnippetsTest < ActiveSupport::TestCase
     assert_equal(MCP::Configuration::DEFAULT_PROTOCOL_VERSION, run_code_snippet("unset_server_protocol_version").chomp)
   end
 
+  test "Tools examples work exactly as documented in README" do
+    assert_json_lines(
+      [
+        { jsonrpc: "2.0", id: "1", result: { content: [{ type: "text", text: "OK" }], isError: false } },
+      ],
+      run_code_snippet("tool_class_definition"),
+    )
+
+    skip "FIXME: this next code snippet is invalid and there doesn't seem to be a way to make both pass..."
+
+    assert_json_lines(
+      [
+        { jsonrpc: "2.0", id: "1", result: { content: [{ type: "text", text: "OK" }], isError: false } },
+      ],
+      run_code_snippet("tool_definition_with_block"),
+    )
+  end
+
   private
 
   def assert_json_lines(expected, actual, message = "Expected the given JSON lines")