pp-wp-snippet-list-shortcodes.php

<?php
// This code snippet adds a meta box in the right sidebar of the post screen that lists all available shortcodes

// As we use a default WordPress admin meta box the box can be closed to save space and opened when needed

// Add a custom function to create the meta box
add_action( 'add_meta_boxes', 'add_shortcodes_metabox' );

// This function adds the meta box
function add_shortcodes_metabox() {
  
  add_meta_box( 'shortcodes-metabox', 'Available Shortcodes', 'display_shortcodes', 'post', 'side', 'high' );
  // The parameter 'post' makes sure the meta box shows only on the post screen
  // If you want it also to appear on the pages screen change 'post' to array( 'post', 'page' )
  
}

// This function creates the content of the meta box
// We don't have to care about all the other stuff because this is done by add_meta_box
function display_shortcodes() {
  
  // The available shortcodes are stored in the global variable $shortcode_tags, so we need access to it
  global $shortcode_tags;
  
  // let's sort the list alphabetically 
  $available_shortcodes = $shortcode_tags;
  ksort( $available_shortcodes );
  
  // show an unordered list of available shortcodes
  echo '<ul>';
  foreach ( $available_shortcodes as $key => $value ) {
    echo '<li>' . $key . '</li>';
  }
  echo '</ul>';
}

?>