build-tools

http://developer.android.com/intl/zh-cn/tools/revisions/build-tools.html

可以更新到最新的版本

<sdk>/build-tools/ 下会有多个版本共存。

To use a specific version of the Build Tools in your application project:

Using Eclipse

1. In the root folder of your application project, find the project.properties file.
2. Open the file and specify the Build Tools version by adding a buildtools property on a separate line:

   sdk.buildtools=17.0.0

Using Android Studio

1. In the root folder of your application project, find the build.gradle file.
2. Open the file and specify the Build Tools version by adding a buildToolsVersion property to the android section:

   android {
       ...
       buildToolsVersion "17.0.0"
       ...
   }

build-tools

原文：http://www.cnblogs.com/cute/p/4952787.html