This snippet shows how to pull an Advanced Custom Fields (ACF) field value into the auto-generated meta description.

tsf-acf-description-snippet.php

<?php
// Do not include the PHP opening tag if PHP is already open.

/**
 * ACF Description Snippet for The SEO Framework
 *
 * This snippet shows how to pull an Advanced Custom Fields (ACF) field value
 * into the auto-generated meta description. Two approaches are demonstrated:
 *
 * 1. With HTML -- When your ACF field stores rich/HTML content, use
 *    `tsf_acf_meta_desc_with_html()`. It strips tags intelligently via
 *    TSF's `extract_content()` so that block-level elements become proper
 *    sentence breaks instead of glued-together words.
 *
 * 2. Without HTML -- When your ACF field already stores plain text, use
 *    `tsf_acf_meta_desc_without_html()`. It returns the value as-is,
 *    falling back to the original excerpt when the field is empty.
 *
 * How to use:
 *   1. Copy ONE of the two examples below into your theme's functions.php
 *      or a custom plugin file.
 *   2. Replace 'my_custom_field_name' with the ACF field name you want.
 *   3. (Optional) Adjust the post-type or query-type guard to narrow
 *      which pages are affected.
 *
 * @package The_SEO_Framework\Snippets
 */

// -- Example 1: ACF field that contains HTML ---------------------------------

add_filter( 'the_seo_framework_description_excerpt', 'tsf_acf_meta_desc_with_html', 10, 3 );
/**
 * Replaces the auto-generated meta description with an ACF field value
 * that may contain HTML markup.
 *
 * The HTML is converted to plain text via TSF's extract_content() helper,
 * which respects block-level tags (e.g. <p>, <div>) as word boundaries so
 * the resulting sentence reads naturally.
 *
 * Falls back to the original excerpt when the ACF field is empty or when
 * the current request is not a singular post/page view.
 *
 * @param string     $excerpt The auto-generated excerpt.
 * @param array|null $args    Query args ( [ 'id', 'tax', 'pta', 'uid' ] ) or null.
 * @param string     $type    Description type: 'search', 'opengraph', 'twitter'.
 * @return string The replacement description, or the original excerpt.
 */
function tsf_acf_meta_desc_with_html( $excerpt, $args, $type ) {

	// Bail early when ACF is not active on this site.
	if ( ! function_exists( 'get_field' ) )
		return $excerpt;

	// Resolve the post ID from the supplied args, or from the current query.
	if ( isset( $args['id'] ) ) {
		$post_id = (int) $args['id'];
	} else {
		// Only proceed on singular (post/page) views.
		if ( 'single' !== \The_SEO_Framework\get_query_type_from_args( $args ) )
			return $excerpt;

		$post_id = tsf()->query()->get_the_real_id();
	}

	// Grab the raw HTML value from ACF. Change the field name to match yours.
	$html = get_field( 'my_custom_field_name', $post_id );

	if ( ! $html )
		return $excerpt;

	// Strip tags while preserving natural word boundaries between blocks.
	$text = tsf()->format()->html()->extract_content( $html );

	return $text ?: $excerpt;
}

// -- Example 2: ACF field that contains plain text ---------------------------

add_filter( 'the_seo_framework_description_excerpt', 'tsf_acf_meta_desc_without_html', 10, 3 );
/**
 * Replaces the auto-generated meta description with an ACF plain-text
 * field value.
 *
 * Use this variant when your ACF field already stores plain text (e.g. a
 * "Text" or "Text Area" field type). No HTML processing is performed;
 * the value is returned directly.
 *
 * Falls back to the original excerpt when the ACF field is empty or when
 * the current request is not a singular post/page view.
 *
 * @param string     $excerpt The auto-generated excerpt.
 * @param array|null $args    Query args ( [ 'id', 'tax', 'pta', 'uid' ] ) or null.
 * @param string     $type    Description type: 'search', 'opengraph', 'twitter'.
 * @return string The replacement description, or the original excerpt.
 */
function tsf_acf_meta_desc_without_html( $excerpt, $args, $type ) {

	// Bail early when ACF is not active on this site.
	if ( ! function_exists( 'get_field' ) )
		return $excerpt;

	// Resolve the post ID from the supplied args, or from the current query.
	if ( isset( $args['id'] ) ) {
		$post_id = (int) $args['id'];
	} else {
		// Only proceed on singular (post/page) views.
		if ( 'single' !== \The_SEO_Framework\get_query_type_from_args( $args ) )
			return $excerpt;

		$post_id = tsf()->query()->get_the_real_id();
	}

	// Return the plain-text ACF value, falling back to the original excerpt.
	return get_field( 'my_custom_field_name', $post_id ) ?: $excerpt;
}