By default Rails’ source annotation rake tasks (notes and its more specific children notes:todo, notes:fixme, etc.) only search the app, config, lib, scripts and test directories of your application. I use RSpec, and on short notice, dumping this file into lib/tasks of my application was the best I could come up with to add spec to the annotation search path.

task :add_rspec_annotation_support do
  SourceAnnotationExtractor.class_eval do
    def self.enumerate(tag, options = {})
      extractor = new(tag)
      extractor.display(extractor.find(%w(app config lib script test spec)), options)
    end
  end
end

%w(notes notes:todo notes:fixme notes:optimize).each do |task|
  Rake::Task[task].enhance([:add_rspec_annotation_support])
end

(I know some people consider littering your code with notes to your future self [or future replacement] to investigate and fix things is a smell that could indicate you’re lazy and/or bad at prioritizing. They may well be right, but until I retrain myself, this helps.)