The official Yii project site now supports OpenSearch. This means you can customize your browser's search box to enable direct search of the content in yiiframework.com. For example, by entering a Yii class name in the browser's search box, the corresponding class API page will be shown in the browser.
One can control the detail of a web application in the webroot/index.php file by manipulating the values of YII_DEBUG and YII_TRACE_LEVEL, but these don't appear to be used by console applications. This is because although the base CApplication class defines a displayError() method that does consider these variable, CConsoleApplication overrides it with a function that doesn't honor them.