This is a simple MediaWiki extension to give you control over the HTML title and meta tags via a tag or parser function.
You can get the extension via Git:
git clone https://github.com/andru/wiki-seo.git
Or download it as zip archive.
In either case, the "WikiSEO" extension should end up in the "extensions" directory of your MediaWiki installation. If you got the zip archive, you will need to put it into a directory called WikiSEO.
Add the following line to the end of your LocalSettings file:
require_once "$IP/extensions/WikiSEO/WikiSEO.php";
Note that prior to version 1.1.1 of this extension the call was
require_once "$IP/extensions/WikiSEO/WikiSEO.setup.php";
This is a lecacy call that will be dropped in a future version of this extension. Because of this you are advised to change your current call to the new one.
Use this extension as described on the extensions documentation page.