[et] Fixup help text a bit (#51930)

The multiline string literal retains the newlines.
diff --git a/tools/engine_tool/lib/src/commands/build_command.dart b/tools/engine_tool/lib/src/commands/build_command.dart
index cbd45ee..e8ad7fd 100644
--- a/tools/engine_tool/lib/src/commands/build_command.dart
+++ b/tools/engine_tool/lib/src/commands/build_command.dart
@@ -41,9 +41,11 @@
   String get name => 'build';
 
   @override
-  String get description => 'Builds the engine'
-      'et build //flutter/fml/...             # Build all targets in `//flutter/fml/`'
-      'et build //flutter/fml:fml_benchmarks  # Build a specific target in `//flutter/fml/`';
+  String get description => '''
+Builds the engine
+et build //flutter/fml/...             # Build all targets in `//flutter/fml/`
+et build //flutter/fml:fml_benchmarks  # Build a specific target in `//flutter/fml/`
+''';
 
   @override
   Future<int> run() async {
diff --git a/tools/engine_tool/lib/src/commands/query_command.dart b/tools/engine_tool/lib/src/commands/query_command.dart
index 5dfe175..e0b3879 100644
--- a/tools/engine_tool/lib/src/commands/query_command.dart
+++ b/tools/engine_tool/lib/src/commands/query_command.dart
@@ -163,9 +163,11 @@
   String get name => 'targets';
 
   @override
-  String get description => 'Provides information about build targets'
-      'et query targets --testonly         # List only test targets'
-      'et query targets //flutter/fml/...  # List all targets under `//flutter/fml`';
+  String get description => '''
+Provides information about build targets
+et query targets --testonly         # List only test targets
+et query targets //flutter/fml/...  # List all targets under `//flutter/fml`
+''';
 
   @override
   Future<int> run() async {
diff --git a/tools/engine_tool/lib/src/commands/run_command.dart b/tools/engine_tool/lib/src/commands/run_command.dart
index 61f289c..efcd5ad 100644
--- a/tools/engine_tool/lib/src/commands/run_command.dart
+++ b/tools/engine_tool/lib/src/commands/run_command.dart
@@ -42,11 +42,13 @@
   String get name => 'run';
 
   @override
-  String get description => 'Run a Flutter app with a local engine build. '
-      'All arguments after -- are forwarded to flutter run, e.g.: '
-      'et run -- --profile '
-      'et run -- -d macos '
-      'See `flutter run --help` for a listing';
+  String get description => '''
+Run a Flutter app with a local engine build.
+  All arguments after -- are forwarded to flutter run, e.g.:
+  et run -- --profile
+  et run -- -d macos
+See `flutter run --help` for a listing
+''';
 
   Build? _lookup(String configName) {
     final String demangledName = demangleConfigName(environment, configName);
diff --git a/tools/engine_tool/lib/src/commands/test_command.dart b/tools/engine_tool/lib/src/commands/test_command.dart
index fe75fb2..a236087 100644
--- a/tools/engine_tool/lib/src/commands/test_command.dart
+++ b/tools/engine_tool/lib/src/commands/test_command.dart
@@ -37,9 +37,11 @@
   String get name => 'test';
 
   @override
-  String get description => 'Runs a test target'
-      'et test //flutter/fml/...             # Run all test targets in `//flutter/fml/`'
-      'et test //flutter/fml:fml_benchmarks  # Run a single test target in `//flutter/fml/`';
+  String get description => '''
+Runs a test target
+et test //flutter/fml/...             # Run all test targets in `//flutter/fml/`
+et test //flutter/fml:fml_benchmarks  # Run a single test target in `//flutter/fml/`
+''';
 
   @override
   Future<int> run() async {