Default abilities fail to register: `wp_abilities_api_init` hook fires before adapter initializes

[mdjwel]

Bug Description

The default MCP adapter abilities (mcp-adapter/discover-abilities, mcp-adapter/get-ability-info, mcp-adapter/execute-ability) fail to register because the ability registration hooks are added too late.

Expected Behavior

When the plugin loads, the default abilities should register successfully via the wp_abilities_api_init hook.

Actual Behavior

The abilities are NOT registered because:

1. McpAdapter::instance() defers initialization to rest_api_init (line 64)
2. maybe_create_default_server() is called during init() which runs on rest_api_init
3. But wp_abilities_api_init fires during the init hook (via WP_Abilities_Registry::get_instance())
4. Since rest_api_init fires AFTER init, the add_action('wp_abilities_api_init', ...) calls are too late

Error in Debug Log

[ERROR] WordPress ability 'mcp-adapter/discover-abilities' does not exist.
[ERROR] WordPress ability 'mcp-adapter/get-ability-info' does not exist.
[ERROR] WordPress ability 'mcp-adapter/execute-ability' does not exist.

Root Cause

In includes/Core/McpAdapter.php, the instance() method schedules initialization on rest_api_init:

add_action( 'rest_api_init', array( self::$instance, 'init' ), 15 );

But the wp_abilities_api_init hook fires during init, which happens BEFORE rest_api_init.

Proposed Fix

Move the ability registration hooks out of maybe_create_default_server() and into a new method register_ability_hooks() that's called immediately during instance():

public static function instance(): self {
    if ( ! isset( self::$instance ) ) {
        self::$instance = new self();

        // Register ability hooks IMMEDIATELY so they fire before wp_abilities_api_init
        self::$instance->register_ability_hooks();

        if ( defined( 'WP_CLI' ) && constant( 'WP_CLI' ) ) {
            add_action( 'init', array( self::$instance, 'init' ), 20 );
        } else {
            add_action( 'rest_api_init', array( self::$instance, 'init' ), 15 );
        }
    }
    return self::$instance;
}

private function register_ability_hooks(): void {
    if ( ! apply_filters( 'mcp_adapter_create_default_server', true ) ) {
        return;
    }
    add_action( 'wp_abilities_api_categories_init', array( $this, 'register_default_category' ) );
    add_action( 'wp_abilities_api_init', array( $this, 'register_default_abilities' ) );
}

Environment

• WordPress: 6.9.0
• MCP Adapter: 0.4.1
• PHP: 7.4+

Steps to Reproduce

1. Install MCP Adapter plugin v0.4.1
2. Activate the plugin
3. Make a REST API request to /wp-json/mcp/mcp-adapter-default-server
4. Check wp-content/debug.log for errors about missing abilities

[gelakhubutia]

I think this is exacly what I experiencing. no matter how I register abilities I do not see it in mcp

[scottblackburn]

Hi @gelakhubutia @mdjwel have you tried adding this meta when registering abilities:

            'meta' => array(
                'mcp' => array(
                    'public' => true,  // Required for MCP default server access
                ),
            )