diff --git a/src/wp-includes/fonts.php b/src/wp-includes/fonts.php
index dfd0b45857..9940761e73 100644
--- a/src/wp-includes/fonts.php
+++ b/src/wp-includes/fonts.php
@@ -53,28 +53,30 @@ function wp_print_font_faces( $fonts = array() ) {
 }
 
 /**
- * Registers a new Font Collection in the Font Library.
+ * Registers a new font collection in the font library.
+ *
+ * See {@link https://schemas.wp.org/trunk/font-collection.json} for the schema
+ * the font collection data must adhere to.
  *
  * @since 6.5.0
  *
- * @param string       $slug Font collection slug. May only contain alphanumeric characters, dashes,
+ * @param string $slug Font collection slug. May only contain alphanumeric characters, dashes,
  *                     and underscores. See sanitize_title().
- * @param array|string $data_or_file {
- *     Font collection data array or a path/URL to a JSON file containing the font collection.
+ * @param array  $args {
+ *     Font collection data.
  *
- *     @link https://schemas.wp.org/trunk/font-collection.json
- *
- *     @type string $name           Required. Name of the font collection shown in the Font Library.
- *     @type string $description    Optional. A short descriptive summary of the font collection. Default empty.
- *     @type array  $font_families  Required. Array of font family definitions that are in the collection.
- *     @type array  $categories     Optional. Array of categories, each with a name and slug, that are used by the
- *                                  fonts in the collection. Default empty.
+ *     @type string       $name          Required. Name of the font collection shown in the Font Library.
+ *     @type string       $description   Optional. A short descriptive summary of the font collection. Default empty.
+ *     @type array|string $font_families Required. Array of font family definitions that are in the collection,
+ *                                       or a string containing the path or URL to a JSON file containing the font collection.
+ *     @type array        $categories    Optional. Array of categories, each with a name and slug, that are used by the
+ *                                       fonts in the collection. Default empty.
  * }
  * @return WP_Font_Collection|WP_Error A font collection if it was registered
  *                                     successfully, or WP_Error object on failure.
  */
-function wp_register_font_collection( $slug, $data_or_file ) {
-	return WP_Font_Library::get_instance()->register_font_collection( $slug, $data_or_file );
+function wp_register_font_collection( string $slug, array $args ) {
+	return WP_Font_Library::get_instance()->register_font_collection( $slug, $args );
 }
 
 /**
@@ -85,7 +87,7 @@ function wp_register_font_collection( $slug, $data_or_file ) {
  * @param string $slug Font collection slug.
  * @return bool True if the font collection was unregistered successfully, else false.
  */
-function wp_unregister_font_collection( $slug ) {
+function wp_unregister_font_collection( string $slug ) {
 	return WP_Font_Library::get_instance()->unregister_font_collection( $slug );
 }
 
@@ -196,5 +198,34 @@ function _wp_before_delete_font_face( $post_id, $post ) {
  * @since 6.5.0
  */
 function _wp_register_default_font_collections() {
-	wp_register_font_collection( 'google-fonts', 'https://s.w.org/images/fonts/17.7/collections/google-fonts-with-preview.json' );
+	wp_register_font_collection(
+		'google-fonts',
+		array(
+			'name'          => _x( 'Google Fonts', 'font collection name' ),
+			'description'   => __( 'Install from Google Fonts. Fonts are copied to and served from your site.' ),
+			'font_families' => 'https://s.w.org/images/fonts/17.7/collections/google-fonts-with-preview.json',
+			'categories'    => array(
+				array(
+					'name' => _x( 'Sans Serif', 'font category' ),
+					'slug' => 'sans-serif',
+				),
+				array(
+					'name' => _x( 'Display', 'font category' ),
+					'slug' => 'display',
+				),
+				array(
+					'name' => _x( 'Serif', 'font category' ),
+					'slug' => 'serif',
+				),
+				array(
+					'name' => _x( 'Handwriting', 'font category' ),
+					'slug' => 'handwriting',
+				),
+				array(
+					'name' => _x( 'Monospace', 'font category' ),
+					'slug' => 'monospace',
+				),
+			),
+		)
+	);
 }
diff --git a/src/wp-includes/fonts/class-wp-font-collection.php b/src/wp-includes/fonts/class-wp-font-collection.php
index 889d1af998..b915e3ea58 100644
--- a/src/wp-includes/fonts/class-wp-font-collection.php
+++ b/src/wp-includes/fonts/class-wp-font-collection.php
@@ -46,12 +46,11 @@ final class WP_Font_Collection {
 	 *
 	 * @since 6.5.0
 	 *
-	 * @param string       $slug         Font collection slug.
-	 * @param array|string $data_or_file Font collection data array or a path/URL to a JSON file
-	 *                                   containing the font collection.
-	 *                                   See {@see wp_register_font_collection()} for the supported fields.
+	 * @param string $slug Font collection slug. May only contain alphanumeric characters, dashes,
+	 *                     and underscores. See sanitize_title().
+	 * @param array  $args Font collection data. See wp_register_font_collection() for information on accepted arguments.
 	 */
-	public function __construct( $slug, $data_or_file ) {
+	public function __construct( string $slug, array $args ) {
 		$this->slug = sanitize_title( $slug );
 		if ( $this->slug !== $slug ) {
 			_doing_it_wrong(
@@ -62,12 +61,17 @@ final class WP_Font_Collection {
 			);
 		}
 
-		if ( is_array( $data_or_file ) ) {
-			$this->data = $this->sanitize_and_validate_data( $data_or_file );
-		} else {
+		$required_properties = array( 'name', 'font_families' );
+
+		if ( isset( $args['font_families'] ) && is_string( $args['font_families'] ) ) {
 			// JSON data is lazy loaded by ::get_data().
-			$this->src = $data_or_file;
+			$this->src = $args['font_families'];
+			unset( $args['font_families'] );
+
+			$required_properties = array( 'name' );
 		}
+
+		$this->data = $this->sanitize_and_validate_data( $args, $required_properties );
 	}
 
 	/**
@@ -78,8 +82,12 @@ final class WP_Font_Collection {
 	 * @return array|WP_Error An array containing the font collection data, or a WP_Error on failure.
 	 */
 	public function get_data() {
+		if ( is_wp_error( $this->data ) ) {
+			return $this->data;
+		}
+
 		// If the collection uses JSON data, load it and cache the data/error.
-		if ( $this->src && empty( $this->data ) ) {
+		if ( isset( $this->src ) ) {
 			$this->data = $this->load_from_json( $this->src );
 		}
 
@@ -116,7 +124,26 @@ final class WP_Font_Collection {
 			return new WP_Error( 'font_collection_json_missing', $message );
 		}
 
-		return $url ? $this->load_from_url( $url ) : $this->load_from_file( $file );
+		$data = $url ? $this->load_from_url( $url ) : $this->load_from_file( $file );
+
+		if ( is_wp_error( $data ) ) {
+			return $data;
+		}
+
+		$data = array(
+			'name'          => $this->data['name'],
+			'font_families' => $data['font_families'],
+		);
+
+		if ( isset( $this->data['description'] ) ) {
+			$data['description'] = $this->data['description'];
+		}
+
+		if ( isset( $this->data['categories'] ) ) {
+			$data['categories'] = $this->data['categories'];
+		}
+
+		return $data;
 	}
 
 	/**
@@ -134,7 +161,7 @@ final class WP_Font_Collection {
 			return new WP_Error( 'font_collection_decode_error', __( 'Error decoding the font collection JSON file contents.' ) );
 		}
 
-		return $this->sanitize_and_validate_data( $data );
+		return $this->sanitize_and_validate_data( $data, array( 'font_families' ) );
 	}
 
 	/**
@@ -154,8 +181,14 @@ final class WP_Font_Collection {
 		if ( false === $data ) {
 			$response = wp_safe_remote_get( $url );
 			if ( is_wp_error( $response ) || 200 !== wp_remote_retrieve_response_code( $response ) ) {
-				// translators: %s: Font collection URL.
-				return new WP_Error( 'font_collection_request_error', sprintf( __( 'Error fetching the font collection data from "%s".' ), $url ) );
+				return new WP_Error(
+					'font_collection_request_error',
+					sprintf(
+						// translators: %s: Font collection URL.
+						__( 'Error fetching the font collection data from "%s".' ),
+						$url
+					)
+				);
 			}
 
 			$data = json_decode( wp_remote_retrieve_body( $response ), true );
@@ -164,7 +197,7 @@ final class WP_Font_Collection {
 			}
 
 			// Make sure the data is valid before storing it in a transient.
-			$data = $this->sanitize_and_validate_data( $data );
+			$data = $this->sanitize_and_validate_data( $data, array( 'font_families' ) );
 			if ( is_wp_error( $data ) ) {
 				return $data;
 			}
@@ -180,14 +213,14 @@ final class WP_Font_Collection {
 	 *
 	 * @since 6.5.0
 	 *
-	 * @param array $data Font collection data to sanitize and validate.
+	 * @param array $data                Font collection data to sanitize and validate.
+	 * @param array $required_properties Required properties that must exist in the passed data.
 	 * @return array|WP_Error Sanitized data if valid, otherwise a WP_Error instance.
 	 */
-	private function sanitize_and_validate_data( $data ) {
+	private function sanitize_and_validate_data( $data, $required_properties = array() ) {
 		$schema = self::get_sanitization_schema();
 		$data   = WP_Font_Utils::sanitize_from_schema( $data, $schema );
 
-		$required_properties = array( 'name', 'font_families' );
 		foreach ( $required_properties as $property ) {
 			if ( empty( $data[ $property ] ) ) {
 				$message = sprintf(
diff --git a/src/wp-includes/fonts/class-wp-font-library.php b/src/wp-includes/fonts/class-wp-font-library.php
index f9ca903271..3069ecb582 100644
--- a/src/wp-includes/fonts/class-wp-font-library.php
+++ b/src/wp-includes/fonts/class-wp-font-library.php
@@ -37,15 +37,14 @@ class WP_Font_Library {
 	 *
 	 * @since 6.5.0
 	 *
-	 * @param string $slug         Font collection slug.
-	 * @param array  $data_or_file Font collection data array or a path/URL to a JSON file
-	 *                             containing the font collection.
-	 *                             See {@see wp_register_font_collection()} for the supported fields.
+	 * @param string $slug Font collection slug. May only contain alphanumeric characters, dashes,
+	 *                     and underscores. See sanitize_title().
+	 * @param array  $args Font collection data. See wp_register_font_collection() for information on accepted arguments.
 	 * @return WP_Font_Collection|WP_Error A font collection if it was registered successfully,
 	 *                                     or WP_Error object on failure.
 	 */
-	public function register_font_collection( $slug, $data_or_file ) {
-		$new_collection = new WP_Font_Collection( $slug, $data_or_file );
+	public function register_font_collection( string $slug, array $args ) {
+		$new_collection = new WP_Font_Collection( $slug, $args );
 
 		if ( $this->is_collection_registered( $new_collection->slug ) ) {
 			$error_message = sprintf(
@@ -72,7 +71,7 @@ class WP_Font_Library {
 	 * @param string $slug Font collection slug.
 	 * @return bool True if the font collection was unregistered successfully and false otherwise.
 	 */
-	public function unregister_font_collection( $slug ) {
+	public function unregister_font_collection( string $slug ) {
 		if ( ! $this->is_collection_registered( $slug ) ) {
 			_doing_it_wrong(
 				__METHOD__,
@@ -94,7 +93,7 @@ class WP_Font_Library {
 	 * @param string $slug Font collection slug.
 	 * @return bool True if the font collection is registered and false otherwise.
 	 */
-	private function is_collection_registered( $slug ) {
+	private function is_collection_registered( string $slug ) {
 		return array_key_exists( $slug, $this->collections );
 	}
 
@@ -117,7 +116,7 @@ class WP_Font_Library {
 	 * @param string $slug Font collection slug.
 	 * @return WP_Font_Collection|null Font collection object, or null if the font collection doesn't exist.
 	 */
-	public function get_font_collection( $slug ) {
+	public function get_font_collection( string $slug ) {
 		if ( $this->is_collection_registered( $slug ) ) {
 			return $this->collections[ $slug ];
 		}
diff --git a/src/wp-includes/rest-api/endpoints/class-wp-rest-font-collections-controller.php b/src/wp-includes/rest-api/endpoints/class-wp-rest-font-collections-controller.php
index 3ede1dacdc..b409af4fc2 100644
--- a/src/wp-includes/rest-api/endpoints/class-wp-rest-font-collections-controller.php
+++ b/src/wp-includes/rest-api/endpoints/class-wp-rest-font-collections-controller.php
@@ -104,7 +104,7 @@ class WP_REST_Font_Collections_Controller extends WP_REST_Controller {
 		$response = rest_ensure_response( $items );
 
 		$response->header( 'X-WP-Total', (int) $total_items );
-		$response->header( 'X-WP-TotalPages', (int) $max_pages );
+		$response->header( 'X-WP-TotalPages', $max_pages );
 
 		$request_params = $request->get_query_params();
 		$collection_url = rest_url( $this->namespace . '/' . $this->rest_base );
diff --git a/tests/phpunit/tests/fonts/font-library/wpFontCollection/getData.php b/tests/phpunit/tests/fonts/font-library/wpFontCollection/getData.php
index 0921379b80..97ea664d48 100644
--- a/tests/phpunit/tests/fonts/font-library/wpFontCollection/getData.php
+++ b/tests/phpunit/tests/fonts/font-library/wpFontCollection/getData.php
@@ -40,11 +40,17 @@ class Tests_Fonts_WpFontCollection_GetData extends WP_UnitTestCase {
 		$mock_file = wp_tempnam( 'my-collection-data-' );
 		file_put_contents( $mock_file, wp_json_encode( $config ) );
 
-		$collection = new WP_Font_Collection( $slug, $mock_file );
+		$collection = new WP_Font_Collection(
+			$slug,
+			array_merge(
+				$config,
+				array( 'font_families' => $mock_file )
+			)
+		);
 		$data       = $collection->get_data();
 
 		$this->assertSame( $slug, $collection->slug, 'The slug should match.' );
-		$this->assertSame( $expected_data, $data, 'The collection data should match.' );
+		$this->assertEqualSetsWithIndex( $expected_data, $data, 'The collection data should match.' );
 	}
 
 	/**
@@ -58,13 +64,21 @@ class Tests_Fonts_WpFontCollection_GetData extends WP_UnitTestCase {
 		add_filter( 'pre_http_request', array( $this, 'mock_request' ), 10, 3 );
 
 		self::$mock_collection_data = $config;
-		$collection                 = new WP_Font_Collection( $slug, 'https://example.com/fonts/mock-font-collection.json' );
+		$collection                 = new WP_Font_Collection(
+			$slug,
+			array_merge(
+				$config,
+				array(
+					'font_families' => 'https://example.com/fonts/mock-font-collection.json',
+				)
+			)
+		);
 		$data                       = $collection->get_data();
 
 		remove_filter( 'pre_http_request', array( $this, 'mock_request' ) );
 
 		$this->assertSame( $slug, $collection->slug, 'The slug should match.' );
-		$this->assertSame( $expected_data, $data, 'The collection data should match.' );
+		$this->assertEqualSetsWithIndex( $expected_data, $data, 'The collection data should match.' );
 	}
 
 	/**
@@ -74,7 +88,6 @@ class Tests_Fonts_WpFontCollection_GetData extends WP_UnitTestCase {
 	 */
 	public function data_create_font_collection() {
 		return array(
-
 			'font collection with required data' => array(
 				'slug'          => 'my-collection',
 				'config'        => array(
@@ -185,7 +198,6 @@ class Tests_Fonts_WpFontCollection_GetData extends WP_UnitTestCase {
 					),
 				),
 			),
-
 		);
 	}
 
@@ -202,8 +214,8 @@ class Tests_Fonts_WpFontCollection_GetData extends WP_UnitTestCase {
 
 		$this->assertWPError( $data, 'Error is not returned when property is missing or invalid.' );
 		$this->assertSame(
-			$data->get_error_code(),
 			'font_collection_missing_property',
+			$data->get_error_code(),
 			'Incorrect error code when property is missing or invalid.'
 		);
 	}
@@ -243,13 +255,19 @@ class Tests_Fonts_WpFontCollection_GetData extends WP_UnitTestCase {
 	public function test_should_error_with_invalid_json_file_path() {
 		$this->setExpectedIncorrectUsage( 'WP_Font_Collection::load_from_json' );
 
-		$collection = new WP_Font_Collection( 'my-collection', 'non-existing.json' );
+		$collection = new WP_Font_Collection(
+			'my-collection',
+			array(
+				'name'          => 'My collection',
+				'font_families' => 'non-existing.json',
+			)
+		);
 		$data       = $collection->get_data();
 
 		$this->assertWPError( $data, 'Error is not returned when invalid file path is provided.' );
 		$this->assertSame(
-			$data->get_error_code(),
 			'font_collection_json_missing',
+			$data->get_error_code(),
 			'Incorrect error code when invalid file path is provided.'
 		);
 	}
@@ -258,15 +276,21 @@ class Tests_Fonts_WpFontCollection_GetData extends WP_UnitTestCase {
 		$mock_file = wp_tempnam( 'my-collection-data-' );
 		file_put_contents( $mock_file, 'invalid-json' );
 
-		$collection = new WP_Font_Collection( 'my-collection', $mock_file );
+		$collection = new WP_Font_Collection(
+			'my-collection',
+			array(
+				'name'          => 'Invalid collection',
+				'font_families' => $mock_file,
+			)
+		);
 
 		// phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged -- Testing error response returned by `load_from_json`, not the underlying error from `wp_json_file_decode`.
 		$data = @$collection->get_data();
 
 		$this->assertWPError( $data, 'Error is not returned with invalid json file contents.' );
 		$this->assertSame(
-			$data->get_error_code(),
 			'font_collection_decode_error',
+			$data->get_error_code(),
 			'Incorrect error code with invalid json file contents.'
 		);
 	}
@@ -274,13 +298,19 @@ class Tests_Fonts_WpFontCollection_GetData extends WP_UnitTestCase {
 	public function test_should_error_with_invalid_url() {
 		$this->setExpectedIncorrectUsage( 'WP_Font_Collection::load_from_json' );
 
-		$collection = new WP_Font_Collection( 'my-collection', 'not-a-url' );
+		$collection = new WP_Font_Collection(
+			'my-collection',
+			array(
+				'name'          => 'Invalid collection',
+				'font_families' => 'not-a-url',
+			)
+		);
 		$data       = $collection->get_data();
 
 		$this->assertWPError( $data, 'Error is not returned when invalid url is provided.' );
 		$this->assertSame(
-			$data->get_error_code(),
 			'font_collection_json_missing',
+			$data->get_error_code(),
 			'Incorrect error code when invalid url is provided.'
 		);
 	}
@@ -288,31 +318,43 @@ class Tests_Fonts_WpFontCollection_GetData extends WP_UnitTestCase {
 	public function test_should_error_with_unsuccessful_response_status() {
 		add_filter( 'pre_http_request', array( $this, 'mock_request_unsuccessful_response' ), 10, 3 );
 
-		$collection = new WP_Font_Collection( 'my-collection', 'https://example.com/fonts/missing-collection.json' );
+		$collection = new WP_Font_Collection(
+			'my-collection',
+			array(
+				'name'          => 'Missing collection',
+				'font_families' => 'https://example.com/fonts/missing-collection.json',
+			)
+		);
 		$data       = $collection->get_data();
 
 		remove_filter( 'pre_http_request', array( $this, 'mock_request_unsuccessful_response' ) );
 
 		$this->assertWPError( $data, 'Error is not returned when response is unsuccessful.' );
 		$this->assertSame(
-			$data->get_error_code(),
 			'font_collection_request_error',
-			'Incorrect error code when response is unsuccussful.'
+			$data->get_error_code(),
+			'Incorrect error code when response is unsuccessful.'
 		);
 	}
 
 	public function test_should_error_with_invalid_json_from_url() {
 		add_filter( 'pre_http_request', array( $this, 'mock_request_invalid_json' ), 10, 3 );
 
-		$collection = new WP_Font_Collection( 'my-collection', 'https://example.com/fonts/invalid-collection.json' );
+		$collection = new WP_Font_Collection(
+			'my-collection',
+			array(
+				'name'          => 'Invalid collection',
+				'font_families' => 'https://example.com/fonts/invalid-collection.json',
+			)
+		);
 		$data       = $collection->get_data();
 
 		remove_filter( 'pre_http_request', array( $this, 'mock_request_invalid_json' ) );
 
 		$this->assertWPError( $data, 'Error is not returned when response is invalid json.' );
 		$this->assertSame(
-			$data->get_error_code(),
 			'font_collection_decode_error',
+			$data->get_error_code(),
 			'Incorrect error code when response is invalid json.'
 		);
 	}
diff --git a/tests/phpunit/tests/fonts/font-library/wpRestFontCollectionsController.php b/tests/phpunit/tests/fonts/font-library/wpRestFontCollectionsController.php
index 0f7fe8f9c6..f5af774d0d 100644
--- a/tests/phpunit/tests/fonts/font-library/wpRestFontCollectionsController.php
+++ b/tests/phpunit/tests/fonts/font-library/wpRestFontCollectionsController.php
@@ -38,7 +38,13 @@ class Tests_REST_WpRestFontCollectionsController extends WP_Test_REST_Controller
 		$mock_file       = wp_tempnam( 'my-collection-data-' );
 		file_put_contents( $mock_file, '{"name": "Mock Collection", "font_families": [ "mock" ], "categories": [ "mock" ] }' );
 
-		wp_register_font_collection( 'mock-col-slug', $mock_file );
+		wp_register_font_collection(
+			'mock-col-slug',
+			array(
+				'name'          => 'My collection',
+				'font_families' => $mock_file,
+			)
+		);
 	}
 
 	public static function wpTearDownAfterClass() {
@@ -78,7 +84,13 @@ class Tests_REST_WpRestFontCollectionsController extends WP_Test_REST_Controller
 		$this->setExpectedIncorrectUsage( 'WP_Font_Collection::load_from_json' );
 
 		wp_set_current_user( self::$admin_id );
-		wp_register_font_collection( 'invalid-collection', 'invalid-collection-file' );
+		wp_register_font_collection(
+			'invalid-collection',
+			array(
+				'name'          => 'My collection',
+				'font_families' => 'invalid-collection-file',
+			)
+		);
 
 		$request  = new WP_REST_Request( 'GET', '/wp/v2/font-collections' );
 		$response = rest_get_server()->dispatch( $request );
@@ -132,14 +144,20 @@ class Tests_REST_WpRestFontCollectionsController extends WP_Test_REST_Controller
 
 		wp_set_current_user( self::$admin_id );
 		$slug = 'invalid-collection';
-		wp_register_font_collection( $slug, 'invalid-collection-file' );
+		wp_register_font_collection(
+			$slug,
+			array(
+				'name'          => 'My collection',
+				'font_families' => 'invalid-collection-file',
+			)
+		);
 
 		$request  = new WP_REST_Request( 'GET', '/wp/v2/font-collections/' . $slug );
 		$response = rest_get_server()->dispatch( $request );
 
 		wp_unregister_font_collection( $slug );
 
-		$this->assertErrorResponse( 'font_collection_json_missing', $response, 500, 'When the collection json file is invalid, the response should return an error for "font_collection_json_missing" with 500 status.' );
+		$this->assertErrorResponse( 'font_collection_json_missing', $response, 500 );
 	}
 
 	/**
@@ -150,11 +168,11 @@ class Tests_REST_WpRestFontCollectionsController extends WP_Test_REST_Controller
 
 		wp_set_current_user( 0 );
 		$response = rest_get_server()->dispatch( $request );
-		$this->assertErrorResponse( 'rest_cannot_read', $response, 401, 'The response status should be 401 for non-authenticated users.' );
+		$this->assertErrorResponse( 'rest_cannot_read', $response, 401 );
 
 		wp_set_current_user( self::$editor_id );
 		$response = rest_get_server()->dispatch( $request );
-		$this->assertErrorResponse( 'rest_cannot_read', $response, 403, 'The response status should be 403 for users without the right permissions.' );
+		$this->assertErrorResponse( 'rest_cannot_read', $response, 403 );
 	}
 
 	/**