Register Custom Taxonomy is a WordPress ability from Advanced Custom Fields — usable via Easy MCP AI, which connects Claude, ChatGPT, and any AI assistant to your site.
Install Free Plugin →Register Custom Taxonomy
WriteRegister a brand-new custom taxonomy (e.g. "Genre", "Color") in WordPress.
Requires Advanced Custom Fields (ACF) 6.8.0+ on a WordPress install where the Abilities API is available (native from WordPress 6.9, or via a compatible Abilities/Feature API polyfill). ACF's global 'Allow AI Access' setting (enable_acf_ai) must be turned on, and each individual field group, custom post type, or custom taxonomy must also have its own 'Allow AI Access' toggle enabled and be exposed in the REST API (show_in_rest) before its abilities are registered. Most abilities additionally require the current user to hold ACF's configured management capability (acf_get_setting('capability'), default manage_options) or the matching WordPress post-type/taxonomy capability (create_posts, edit_posts, delete_posts, manage_terms, edit_terms, delete_terms).
What it does
This ability creates a new taxonomy definition using ACF's taxonomy registration system, including its labels, hierarchy, associated post types, and REST API exposure. It only defines the taxonomy schema itself, not individual terms; once registered (and if AI access and REST exposure are enabled), ACF automatically registers a matching set of query, create, view, update, and delete abilities for terms in that taxonomy. It fails with an error if a taxonomy with the same key already exists.
See it in action
You ask your AI assistant
"Register a new hierarchical taxonomy called "Genre" that applies to the Book post type."
Inputs
| Name | Type | Required | Description |
|---|---|---|---|
| taxonomy | string | Yes | The taxonomy key (slug), lowercase letters, numbers, underscores, and hyphens only, up to 32 characters. |
| label | string | Yes | The singular label for the taxonomy. |
| plural_label | string | Yes | The plural label for the taxonomy. |
| description | string | No | Description of the taxonomy. |
| public | boolean | No | Whether the taxonomy is public. |
| hierarchical | boolean | No | Whether the taxonomy is hierarchical (like categories) or flat (like tags). |
| post_types | array | No | Array of post types this taxonomy applies to. |
| show_in_rest | boolean | No | Whether to show this taxonomy in the REST API. Required for its AI abilities to be registered. |
| rest_base | string | No | Custom REST API base path (defaults to the taxonomy key). |
| allow_ai_access | boolean | No | Whether to allow AI access to this taxonomy. |
| ai_description | string | No | Description to help AI understand the purpose of this taxonomy. |
| show_ui | boolean | No | Whether to generate a default admin UI for managing this taxonomy. |
| show_admin_column | boolean | No | Whether to display a column for the taxonomy on its post type listing screens. |
Returns
An object with a success boolean, the newly registered taxonomy object, and a confirmation message.
Permission
The current user must hold ACF's configured management capability, from acf_get_setting('capability') (defaults to 'manage_options').
More Advanced Custom Fields abilities
ACF Custom Post Types
List all ACF-registered custom post types that AI is allowed to access.
ACF Custom Taxonomies
List all ACF-registered custom taxonomies that AI is allowed to access.
Create Custom Post Type Item
Create a new item in a specific AI-accessible ACF custom post type.
Create Custom Taxonomy Term
Create a new term in a specific AI-accessible ACF custom taxonomy.
Delete Custom Post Type Item
Delete an item from a specific AI-accessible ACF custom post type by ID.
Delete Custom Taxonomy Term
Delete a term from a specific AI-accessible ACF custom taxonomy by ID.