Alternatively use org-agenda-custom-commands to apply org-agenda-prefix-format to a specific search. For example to have C-x a A display items with Active tag without the filename with which they were found:

(setq org-agenda-custom-commands
      (quote (
              ("A" "Active Tags" tags "Active"
               ((org-agenda-overriding-header "My Active items")
                (org-tags-match-list-sublevels t)
                (org-agenda-prefix-format "  %?-12t% s"))))))

Alternatively use org-agenda-custom-commands to apply org-agenda-prefix-format to a specific search. For example to have C-x a A display items with Active tag without the filename with which they were found:

(setq org-agenda-custom-commands
      '(("A" "Active Tags" tags "Active"
         ((org-agenda-overriding-header "My Active items")
          (org-tags-match-list-sublevels t)
          (org-agenda-prefix-format "  %?-12t% s")))))