pkg/analyzer_utilities/lib/tool/README.md - sdk - Git at Google

 This 'tool' directory is similar to the top-level 'tool' directory in other
 packages, except that the source must be importable by tools in other packages
 found in the Dart SDK, so it lives at 'lib/tool'.
	This 'tool' directory is similar to the top-level 'tool' directory in other
	packages, except that the source must be importable by tools in other packages
	found in the Dart SDK, so it lives at 'lib/tool'.