How can we modify an inherited or a system field description in a specific Work Item Type with API

The goal is to be able to modify the description in the WIT layout with Rest API for inherited or system field.

For exemple, the description of the field Description for a WIT Epic is different for a WIT Feature. See below :

Just to be clear, it’s not the global description of the field (like we can see below in the tab fields of the organization) that we want to modify but the description inside a WIT layout.

To clarify I used this API, [https://docs.microsoft.com/en-us/rest/api/azure/devops/processes/fields/update?view=azure-devops-rest-7.1](https://docs.microsoft.com/en-us/rest/api/azure/devops/processes/fields/update?view=azure-devops-rest-7.1).

The description is not modify after the script below is run.

The script :

The response of the request :

The response of the description should be “test”.

Is there an other way to edit it ?