Adds info about commands requiring Flutter-bundled dart
diff --git a/script/tool/README.md b/script/tool/README.md
index 225cda2..a638602 100644
--- a/script/tool/README.md
+++ b/script/tool/README.md
@@ -51,6 +51,8 @@
All examples assume running from source; see above for running the
published version instead.
+Some commands require the Flutter-bundled version of Dart to be the first `dart` loaded into path (or the only version of Dart installed).
+
Most commands take a `--packages` argument to control which package(s) the
command is targetting. An package name can be any of:
- The name of a package (e.g., `path_provider_android`).
