diff --git a/src/fmu/tools/rms/generate_petro_jobs_for_field_update.py b/src/fmu/tools/rms/generate_petro_jobs_for_field_update.py
index 198a34f0..8b5ccf35 100644
--- a/src/fmu/tools/rms/generate_petro_jobs_for_field_update.py
+++ b/src/fmu/tools/rms/generate_petro_jobs_for_field_update.py
@@ -1,3 +1,74 @@
+"""
+Description:
+    This script can be used to generate new petrosim jobs in RMS from an existing
+    petrosim job. The input (original) petrosim job is assumed to be a job for either
+    a single zone or multi zone grid where the petrophysical properties are conditioned
+    to an existing facies realization.
+    The new generated petrosim jobs will not use facies realization as input, but assume
+    that all grid cells belongs to the same facies. Hence, if the original petrosim job
+    specify model parameters for petrophysical properties conditioned to a facies
+    realization with N different facies, this script can generate up to N new
+    petrosim jobs, one per facies the user wants to use in field parameter
+    updating in ERT.
+
+Input:
+    An existing RMS project with a petrophysical job conditioning petrophysical
+    properties on an existing facies realization.
+
+    A yaml format configuration file specifying necessary input to the script.
+    This includes name of original petrosim job, grid model name and for each zone and
+    each facies which petrophysical variables to use in the new petrosim jobs that are
+    created. It is possible to not use all petrophysical variables in the original
+    job and this can vary from facies to facies and zone to zone.
+
+Output:
+    A set of new petrosim jobs, one per facies that is specified in at least
+    one of the zones. For a multi zone grid, each of the new petrosim jobs will
+    contain specification of the petrophysical properties that is to be modelled
+    for each zone for a given facies. The new jobs will get a name reflecting which
+    facies it belongs to.
+
+How to use the new petrosim jobs in the RMS workflow:
+
+    When initial ensemble is created (ERT iteration = 0):
+    The RMS workflow should first use the original petrosim job to generate realizations
+    of petrophysical properties as usual when not all of the petrophysical properties
+    are going to be used as field parameters in RMS. If all petrophysical properties are
+    going to be updated as field parameters in ERT, it is not necessary to do this step.
+    Add all the new petrosim jobs (one per facies) into the workflow in RMS.
+    Copy the petrophysical property realizations for each facies from the geomodel grid
+    into the ERTBOX grid used for field parameter update in ERT.
+    Export the petrophysical properties for each of the facies to ERT in ROFF format.
+    Use a script that take as input the facies realization and the petrophysical
+    properties per facies and use the facies realization as filter to select which
+    values to copy from the petrophysical realizations to put into the petrophysical
+    property parameter that was generated by the original job. This will overwrite the
+    petrophysical properties in the realization from the original job for those
+    parameters that are used as field parameters to be updated by ERT.
+    The other petrophysical parameters generated by the original job but not used as
+    field parameters in ERT will be untouched.
+
+    When updated ensemble is fetched from ERT (ERT iteration > 0):
+    Run the original petrosim job to generate all petrophysical parameters
+    in the geogrid. Import the updated field parameters for petrophysical properties
+    per facies into ERTBOX grid.
+    Copy the petrophysical property parameters that were updated as
+    field parameters by ERT into geomodel grid from the ERTBOX grid.
+    This operation is the same as the last step
+    when initial ensemble realization was created. This step will then overwrite the
+    petrophysical property parameters already created by the original job by the new
+    values updated by ERT. All petrophysical property parameters not updated as field
+    parameters by ERT will be untouched and will therefore have the same values as they
+    had after the original petrosim job was run.
+
+
+Summary:
+
+    The current script is made to simplify the preparation step of the RMS project by
+    creating the necessary petrosim jobs for a workflow supporting simultaneous update
+    of both facies and petrophysical properties in ERT.
+"""
+
 import copy
 import json
 import pprint