Custom abilities

Abilities are operations defined with WordPress's Abilities API. Registering yours through VX gives it VX's shared settings: the administrator permission check, a category, and correct MCP exposure metadata. It then appears on the Abilities tab, where you choose whether assistants may use it.

add_action( 'vxframework/abilities/register', function ( string $registry ) {
    $registry::register( 'my-plugin/count-bookings', [
        'label'            => 'Count bookings',
        'description'      => 'Returns the number of confirmed bookings for a Class. Read-only.',
        'input_schema'     => [
            'type'                 => 'object',
            'properties'           => [ 'class_id' => [ 'type' => 'integer' ] ],
            'required'             => [ 'class_id' ],
            'additionalProperties' => false,
        ],
        'output_schema'    => [ 'type' => 'object' ],
        'execute_callback' => fn( array $input ) => [ 'ok' => true, 'count' => my_count_bookings( $input['class_id'] ) ],
        'meta'             => [ 'mode' => 'read', 'mcp' => [ 'public' => false ] ],
    ] );
} );

Run it from the command line to test:

wp vx-framework abilities run my-plugin/count-bookings --input='{"class_id":123}' --user=admin

Write the description for an AI assistant: say what it does, what it returns, and whether it changes anything. The assistant decides when to call it based on that text.

Things VX doesn't do for you

• Undo and activity logging come from VX's own write abilities. A custom write isn't recorded in the activity log unless you record it yourself.
• Exposure is off. Leave meta.mcp.public at false and turn the ability on from the Abilities tab. Don't rely on meta.public: a separately installed MCP Adapter plugin could publish it outside VX's settings.

Technical details for LLMs

• vxframework/abilities/register passes the class name VxFramework\Modules\Abilities\Registry; call $registry::register( $name, $args ), a wrapper over wp_register_ability() that applies prepare_args(): manage_options permission floor (unless you pass permission_callback), normalized meta (mode, domain, tier, show_in_rest, mcp.public pinned to false when omitted, annotations), category from domain, and for writes the shared description suffix and config lock.
• Return [ 'ok' => false, 'code', 'message' ] for refusals; over MCP they surface as tool errors.
• Test: wp vx-framework abilities list, wp vx-framework abilities run <name> --input=<json>, wp vx-framework abilities mcp.
• Abilities under vx-framework/ are treated as VX's own by the exposure picker; use your own namespace.