public function setDescription($clientId, $description)
	{
		$params = array(
			'for_client_id' => $clientId,
			'description'   => $description,
		);

		// If empty, description is set for the owner client.
		if (!$params['for_client_id']) {
			unset($params['for_client_id']);
		}

		return $this->post('clients/set_description', $params);
	}