changing meta title and description for tags.php
 

may i know the condition which i can put to edit meta title and description for tags.php page by search keyword

I don't understand what you want.

I need to change metatitle and metadescription for only tags.php page.
Please give me the condition which i can put it in the headinclude so that rest of the pages follow defaults to the standard Meta information.
The Meta information for tags.php would be main tag name.

You can just use THIS_SCRIPT for your condition:

I need to put metainfo as tag name but it is not available in headinclude template.
For ex the variable name is {vb:raw criteriaDisplay} which gives me tag name.