diff --git a/mdtest/lib/executable.dart b/mdtest/lib/executable.dart
index d390341..f3a7e6b 100644
--- a/mdtest/lib/executable.dart
+++ b/mdtest/lib/executable.dart
@@ -8,6 +8,7 @@
 import 'package:args/command_runner.dart';
 import 'package:stack_trace/stack_trace.dart';
 
+import 'src/commands/doctor.dart';
 import 'src/commands/create.dart';
 import 'src/commands/run.dart';
 import 'src/commands/auto.dart';
@@ -17,6 +18,7 @@
 
 Future<Null> main(List<String> args) async {
   MDTestCommandRunner runner = new MDTestCommandRunner()
+    ..addCommand(new DoctorCommand())
     ..addCommand(new CreateCommand())
     ..addCommand(new RunCommand())
     ..addCommand(new AutoCommand())
diff --git a/mdtest/lib/src/commands/auto.dart b/mdtest/lib/src/commands/auto.dart
index 8101b2c..bf36e90 100644
--- a/mdtest/lib/src/commands/auto.dart
+++ b/mdtest/lib/src/commands/auto.dart
@@ -23,8 +23,10 @@
 
   @override
   final String description
-    = 'Automatically run applications based on a subset of spec to device '
-      'settings that maximize the device coverage';
+    = 'Automatically install and launch flutter applications on different '
+      'device groups which satisfy the test spec.  mdtest combines test result '
+      'for each round and report it to the user.  Each application is '
+      'guaranteed to be executed on each device group.';
 
   dynamic _specs;
 
@@ -83,7 +85,7 @@
       MDTestRunner runner = new MDTestRunner();
 
       if (await runner.runAllApps(deviceMapping) != 0) {
-        printError('Error when running applications on #Round $roundNum');
+        printError('Error when running applications on Round #$roundNum');
         await uninstallTestingApps(deviceMapping);
         errRounds.add(roundNum);
         printInfo('End of Round #$roundNum\n');
@@ -172,6 +174,7 @@
   }
 
   AutoCommand() {
+    usesBriefFlag();
     usesSpecsOption();
     usesCoverageFlag();
     usesTAPReportOption();
diff --git a/mdtest/lib/src/commands/doctor.dart b/mdtest/lib/src/commands/doctor.dart
new file mode 100644
index 0000000..961255d
--- /dev/null
+++ b/mdtest/lib/src/commands/doctor.dart
@@ -0,0 +1,98 @@
+// Copyright 2016 The Vanadium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:io';
+
+import '../runner/mdtest_command.dart';
+import '../globals.dart';
+
+class DoctorCommand extends MDTestCommand {
+
+  @override
+  final String name = 'doctor';
+
+  @override
+  final String description = 'Check if all dependent tools are installed.';
+
+  @override
+  Future<int> runCore() async {
+    printInfo('Running "mdtest doctor command" ...');
+    if (os.isWindows) {
+      print('Windows platform is not supported.');
+      return 1;
+    }
+    int result = 0;
+    result += printDiagnoseMessage(
+      'dart',
+      'Please install dart following the link https://www.dartlang.org/install '
+      'and add dart/bin to your environment variable PATH.'
+    );
+    result += printDiagnoseMessage(
+      'pub',
+      'Please install dart following the link https://www.dartlang.org/install '
+      'and add dart/bin to your environment variable PATH.'
+    );
+    result += printDiagnoseMessage(
+      'flutter',
+      'Please install flutter following the link https://flutter.io/setup/ '
+      'and add flutter/bin to your environment variable PATH.  Ideally '
+      '`flutter doctor` should not report any problem.'
+    );
+    result += printDiagnoseMessage(
+      'adb',
+      'Please install Android SDK following the link '
+      'https://developer.android.com/studio/intro/update.html '
+      'and add Android/Sdk/platform-tools to your environment variable PATH.'
+    );
+
+    if (os.isMacOS) {
+      result += printDiagnoseMessage(
+        'brew',
+        'Please install homebrew following the link http://brew.sh/.'
+      );
+      result += printDiagnoseMessage(
+        'lcov',
+        'Please install lcov using `brew install lcov`.'
+      );
+      result += printDiagnoseMessage(
+        'mobiledevice',
+        'Please install mobiledevice following the link '
+        'https://github.com/imkira/mobiledevice.'
+      );
+    }
+
+    if (os.isLinux) {
+      result += printDiagnoseMessage(
+        'lcov',
+        'Please install lcov using `sudo apt-get lcov`.'
+      );
+    }
+
+    if (result > 0) {
+      bool singleSyntax = result == 1;
+      printError(
+        'Some tool${singleSyntax ? '' : 's'} that mdtest '
+        'depend${singleSyntax ? 's' : ''} on ${singleSyntax ? 'is' : 'are'} '
+        'not installed.  Please follow the instructions above and resolve '
+        'all problems before using mdtest.'
+      );
+      return 1;
+    }
+    return 0;
+  }
+}
+
+/// Print diagnose message for the given executable and instructions on how
+/// to install the tool if it is not detected or installed.  Returns 0 if
+/// the tool is installed and properly configured, 1 otherwise.
+int printDiagnoseMessage(String exec, String instructions) {
+  File execFile = os.which(exec);
+  if (execFile == null) {
+    print('[x] $exec is not found.  $instructions');
+    return 1;
+  }
+  print('[✓] $exec found in ${execFile.path}.');
+  return 0;
+}
diff --git a/mdtest/lib/src/commands/run.dart b/mdtest/lib/src/commands/run.dart
index 852259e..b640545 100644
--- a/mdtest/lib/src/commands/run.dart
+++ b/mdtest/lib/src/commands/run.dart
@@ -21,7 +21,9 @@
   final String name = 'run';
 
   @override
-  final String description = 'Run multi-device driver tests';
+  final String description
+    = 'Install and launch flutter applications on multiple devices and '
+      'execute test script to collect and report test results to the user.';
 
   dynamic _specs;
 
@@ -112,6 +114,7 @@
   }
 
   RunCommand() {
+    usesBriefFlag();
     usesSpecsOption();
     usesCoverageFlag();
     usesTAPReportOption();
diff --git a/mdtest/lib/src/runner/mdtest_command.dart b/mdtest/lib/src/runner/mdtest_command.dart
index 7a5b3f0..b666227 100644
--- a/mdtest/lib/src/runner/mdtest_command.dart
+++ b/mdtest/lib/src/runner/mdtest_command.dart
@@ -7,6 +7,7 @@
 
 import 'package:args/command_runner.dart';
 
+import '../base/logger.dart';
 import '../globals.dart';
 import 'mdtest_command_runner.dart';
 
@@ -21,12 +22,23 @@
   @override
   MDTestCommandRunner get runner => super.runner;
 
+  bool _usesBriefFlag = false;
   bool _usesSpecsOption = false;
   bool _usesSpecTemplateOption = false;
   bool _usesTestTemplateOption = false;
   bool _usesSaveTestReportOption = false;
   bool _usesReportTypeOption = false;
 
+  void usesBriefFlag() {
+    argParser.addFlag(
+      'brief',
+      abbr: 'b',
+      negatable: false,
+      help: 'Disable logging, only report test execution result.'
+    );
+    _usesBriefFlag = true;
+  }
+
   void usesSpecsOption() {
     argParser.addOption(
       'spec',
@@ -120,6 +132,17 @@
   Validator commandValidator;
 
   bool _commandValidator() {
+    if (_usesBriefFlag) {
+      if (globalResults['verbose'] && argResults['brief']) {
+        printError('--verbose flag conflicts with --brief flag');
+        return false;
+      }
+      if (argResults['brief']) {
+        defaultLogger = new DumbLogger();
+        briefMode = true;
+      }
+    }
+
     if (_usesSpecsOption) {
       String specsPath = argResults['spec'];
       if (specsPath == null) {
diff --git a/mdtest/lib/src/runner/mdtest_command_runner.dart b/mdtest/lib/src/runner/mdtest_command_runner.dart
index e5c9981..965653a 100644
--- a/mdtest/lib/src/runner/mdtest_command_runner.dart
+++ b/mdtest/lib/src/runner/mdtest_command_runner.dart
@@ -22,12 +22,6 @@
       help: 'Noisy logging, including detailed information '
             'through the entire execution.'
     );
-    argParser.addFlag(
-      'brief',
-      abbr: 'b',
-      negatable: false,
-      help: 'Disable logging, only report test execution output.'
-    );
   }
 
   @override
@@ -39,24 +33,10 @@
 
   @override
   Future<int> runCommand(ArgResults globalResults) async {
-    if (!_commandValidator(globalResults)) {
-      return 1;
-    }
     if (globalResults['verbose']) {
       defaultLogger = new VerboseLogger();
     }
-    if (globalResults['brief']) {
-      defaultLogger = new DumbLogger();
-      briefMode = true;
-    }
-    return await super.runCommand(globalResults);
-  }
 
-  bool _commandValidator(ArgResults globalResults) {
-    if (globalResults['verbose'] && globalResults['brief']) {
-      printError('--verbose flag conflicts with --brief flag');
-      return false;
-    }
-    return true;
+    return await super.runCommand(globalResults);
   }
 }