I'm currently using SEO by EtherCreative on Craft 2, one of my pages needs a custom title and description injected into it like this on the docs:
In some cases, you will not have access to an SEO field, but will want to set the page title & description. You can do this by creating a custom SEO object using the function below:
craft.seo.custom('The Page Title', 'The page description', $includeDefaultTitleSuffix)
Mine seems to be throwing errors or not doing anything like so:
{% set seo = craft.seo.custom('Discount codes and vouchers for {{ query }}', 'You searched for {{ query }}. Check out the latest live {{ query }} discount codes & voucher codes for {{ "now"|date("m") }} {{ "now"|date("Y") }} only at Vouchertoday.uk') %}