diff --git a/tools/build_trexio.sh b/tools/build_trexio.sh
index 6c42508..5c1b9ac 100755
--- a/tools/build_trexio.sh
+++ b/tools/build_trexio.sh
@@ -1,13 +1,18 @@
 #!/bin/bash
 
-if [[ $(basename $PWD) != "src" ]] ; then
-  echo "This script should run in the src directory"
+# Check that script is executed from tools directory
+if [[ $(basename $PWD) != "tools" ]] ; then
+  echo "This script should run in the tools directory"
   exit -1
 fi
 
+# Go to src directory
+cd ../src
+
 # We want the script to crash on the 1st error:
 set -e
 
+# Create directories for templates
 echo "create populated directories"
 mkdir -p templates_front/populated
 mkdir -p templates_text/populated
@@ -16,6 +21,7 @@ mkdir -p templates_hdf5/populated
 # It is important to ad '--' to rm because it tells rm that what follows are
 # not options. It is safer.
 
+# Cleaning of existing data
 echo "remove existing templates"
 rm -f -- templates_front/*.{c,h,f90}
 rm -f -- templates_text/*.{c,h}
@@ -26,6 +32,7 @@ rm -f -- templates_front/populated/*
 rm -f -- templates_text/populated/*
 rm -f -- templates_hdf5/populated/*
 
+# Function to produce TREXIO source files from org-mode files
 function tangle()
 {
   local command="(org-babel-tangle-file \"$1\")"
@@ -36,24 +43,27 @@ function tangle()
         --eval "$command"
 }
 
+# Produce source files for front end
 echo "tangle org files to generate templates"
 cd templates_front
 tangle templator_front.org
 cd ..
 
+# Produce source files for TEXT back end
 cd templates_text
 tangle templator_text.org
 cd ..
 
+# Produce source files for HDF5 back end
 cd templates_hdf5
 tangle templator_hdf5.org
 cd ..
 
+# Populate templates with TREXIO structure according to trex.json file
 echo "run generator script to populate templates"
 python3 generator.py
 
-sleep 2
-
+# Put pieces of source files together
 echo "compile populated files in the lib source files "
 cd templates_front
 source build.sh
@@ -70,3 +80,5 @@ source build.sh
 cp trexio* ../
 cd ..
 
+# Come back to the TREXIO root directory
+cd ..