我想在网络管理仪表板上放置一个“工具”菜单项

如果你的意思是在核心顶层之下；仪表板“；菜单，然后您可以使用network_admin_menu hook 随着add_submenu_page() 添加菜单项。

完整工作示例

<?php
/**
 * Plugin Name: WPSE 391799
 * Description: Network Admin custom "Tools" menus
 * Version: 1.0
 */

// Adds the custom Network Admin menus.
add_action( \'network_admin_menu\', \'wpse_391799_add_network_admin_menus\' );
function wpse_391799_add_network_admin_menus() {
    add_submenu_page( \'index.php\',      // parent slug or file name of a standard WordPress admin page
        \'My Tools Page\',                // menu page title
        \'My Tools (Submenu)\',           // menu title
        \'manage_network\',               // user capability required to access the menu (and its page)
        \'my-tools-page\',                // menu slug that\'s used with the "page" query, e.g. ?page=menu-slug
        \'wpse_391799_render_tools_page\' // the function which outputs the page content
    );

    add_menu_page( \'My Tools Page\',      // menu page title
        \'My Tools (Top-Level)\',          // menu title
        \'manage_network\',                // user capability required to access the menu (and its page)
        \'my-tools-page2\',                // menu slug to that\'s with the "page" query, e.g. ?page=menu-slug
        \'wpse_391799_render_tools_page\', // the function which outputs the page content
        \'dashicons-admin-tools\',         // menu icon (in this case, I\'m using a Dashicons icon\'s CSS class)
        24                               // menu position; 24 would place the menu above the "Settings" menu
    );

    add_submenu_page( \'my-tools-page2\',
        \'My Tools Submenu Page\',
        \'My Tools Submenu\',
        \'manage_network\',
        \'my-tools-submenu-page\',
        \'wpse_391799_render_tools_submenu_page\'
    );
}

// Outputs the content for the "My Tools (Submenu)" and "My Tools (Top-Level)" pages.
function wpse_391799_render_tools_page() {
    ?>
        <div class="wrap my-tools-parent">
            <h1><?php echo esc_html( get_admin_page_title() ); ?></h1>
            <p>Foo bar. Bla bla. Your content here.</p>
        </div>
    <?php
}

// Outputs the content for the "My Tools Submenu" page.
function wpse_391799_render_tools_submenu_page() {
    ?>
        <div class="wrap my-tools-submenu">
            <h1><?php echo esc_html( get_admin_page_title() ); ?></h1>
            <p>Foo bar. Bla bla. Your content here.</p>
        </div>
    <?php
}