Why should I configure sdk-tools/platform-toools?

To facilitate the use of the development tools included with the Android SDK, we set the path in the system environment variable to the tools directory under the installation directory of the Android SDK.

In the Android SDK:

There are adb.exe in Platform-tools, Sqlite3.exe (related to SQLite);
There are emulator.exe,ddms.bat in the tools directory;

So, personally understand that in order to be able to invoke these tools directly in any DOS environment, it is necessary to configure platform-tools and tools in the Android SDK.

Why should I configure sdk-tools/platform-toools?