How to Programmatically Override Yoast SEO Meta Descriptions

Yoast SEO pulls each post’s meta description from the editor metabox, but when you run thousands of auto-generated pages or a custom post type fed by an API, typing one by hand is not an option. You set it in code with Yoast’s wpseo_metadesc filter. This DevAnswers guide covers the global override, conditional logic, custom fields, and the duplicate-tag gotcha.

The wpseo_metadesc Filter (Quick Answer) #

Yoast builds the description tag through its Meta_Description_Presenter and runs the text through the wpseo_metadesc filter before printing it to the <head>. Hook a callback that returns your string and Yoast uses that instead. Add the code to a child theme’s functions.php or a code snippets plugin (see where to add code in WordPress); a syntax error in functions.php can white-screen the site, so a snippets plugin is the safer home.

add_filter( 'wpseo_metadesc', function ( $description ) {
    return 'Shop hand-knit Aran wool sweaters, made in Galway and shipped worldwide.';
} );

That replaces the description on every page. You rarely want a single description site-wide, but it shows the core mechanism: return a string, and Yoast renders it in place of its own.

Override Only Specific Pages (Conditional Logic) #

In practice you change the description on certain pages and leave the rest to Yoast. Check the context with a conditional tag such as is_singular() or get_post_type(), and here is the part people get wrong: return the incoming $description unchanged for everything you do not target. Returning an empty string there would blank the description on every other page of the site.

add_filter( 'wpseo_metadesc', function ( $description ) {
    if ( is_singular( 'product' ) ) {
        $year = date( 'Y' );
        return 'In stock now for ' . $year . '. Free delivery across Ireland on orders over EUR 50.';
    }
    return $description; // leave every other page to Yoast
} );

is_singular( 'product' ) returns true only when a single product post is being displayed, so the override is scoped to that one post type. Pass a different slug, or swap in is_category(), is_page(), or a get_post_type() check, to target another context.

Pull the Description From a Custom Field #

Directory and listing sites usually store a summary in a custom field, and you can serve that as the description so every entry gets its own without anyone opening the metabox. With Advanced Custom Fields, read it with get_field(), and guard for an empty value so posts without a summary fall back to Yoast’s default.

add_filter( 'wpseo_metadesc', function ( $description ) {
    if ( is_singular( 'listing' ) ) {
        $summary = get_field( 'seo_summary' );
        if ( $summary ) {
            return wp_strip_all_tags( $summary );
        }
    }
    return $description;
} );

wp_strip_all_tags() keeps stray markup out of the tag. Not using ACF? Swap get_field() for core post meta: get_post_meta( get_the_ID(), 'seo_summary', true ).

Override the Title and Social Description Too #

Yoast manages every head tag through a presenter you can modify or extend, not just the description, so the same callback pattern covers the rest. Use wpseo_title to filter the SEO title tag and wpseo_opengraph_desc to filter the Open Graph (social share) description. If a missing or duplicated title tag is your real problem, see our guide on the WordPress title tag in the header.

add_filter( 'wpseo_title', function ( $title ) {
    if ( is_singular( 'product' ) ) {
        return get_the_title() . ' | DevAnswers Store';
    }
    return $title;
} );

Common Gotchas: Duplicate Tags, Length, and Caching #

Two description tags in your source. Some themes output their own meta description tag, so you will see two <meta name="description"> tags in the page source if yours does. View the source, search for <meta name="description", and if you find two, look in the theme’s SEO options or header.php (ideally via a child theme), since many themes add the excerpt as a description tag by default. Disabling the theme’s own meta output is required to avoid two description tags.

Length. Search results only show a limited slice of the description, so the common recommendation is to keep desktop descriptions to roughly 155 to 160 characters; trim long programmatic strings with mb_substr(). Caching. If you run a caching plugin or a page cache, clear it after adding the code, then reload the page source to confirm the new description.

Summary #

The wpseo_metadesc filter turns Yoast’s description into something you control in code. Return your own string, scope it with a conditional tag, and always return the incoming $description for pages you are not targeting. Pull the text from a custom field for listing sites, reach for wpseo_title and wpseo_opengraph_desc when you need the title or social tags too, and watch for a duplicate description tag left behind by your theme.