diff --git a/tools/hess/Image.py b/tools/hess/Image.py
index 14a8a47..f37bbbd 100644
--- a/tools/hess/Image.py
+++ b/tools/hess/Image.py
@@ -48,9 +48,18 @@
 else:
     inp_pdic = inp_dic
 
-for vn, vv in inp_pdic.items():
-    if vn != "_selector":
-        globals()[vn] = type(globals()[vn])(vv)
+for _vn in [
+    "src_name",
+    "RA",
+    "DEC",
+    "T1",
+    "T2",
+    "Radius",
+    "pixsize",
+    "Emin",
+    "Emax",
+]:
+    globals()[_vn] = type(globals()[_vn])(inp_pdic[_vn])
 
 T1 = Time(T1, format="isot", scale="utc").mjd
 T2 = Time(T2, format="isot", scale="utc").mjd
diff --git a/tools/hess/Lightcurve.py b/tools/hess/Lightcurve.py
index 15495c7..896b2ef 100644
--- a/tools/hess/Lightcurve.py
+++ b/tools/hess/Lightcurve.py
@@ -46,9 +46,19 @@
 else:
     inp_pdic = inp_dic
 
-for vn, vv in inp_pdic.items():
-    if vn != "_selector":
-        globals()[vn] = type(globals()[vn])(vv)
+for _vn in [
+    "src_name",
+    "RA",
+    "DEC",
+    "T1",
+    "T2",
+    "Radius",
+    "R_s",
+    "Emin",
+    "Emax",
+    "NTbins",
+]:
+    globals()[_vn] = type(globals()[_vn])(inp_pdic[_vn])
 
 T1 = Time(T1, format="isot", scale="utc").mjd
 T2 = Time(T2, format="isot", scale="utc").mjd
diff --git a/tools/hess/Spectrum.py b/tools/hess/Spectrum.py
index e9e0b3a..0d658f2 100644
--- a/tools/hess/Spectrum.py
+++ b/tools/hess/Spectrum.py
@@ -54,9 +54,21 @@
 else:
     inp_pdic = inp_dic
 
-for vn, vv in inp_pdic.items():
-    if vn != "_selector":
-        globals()[vn] = type(globals()[vn])(vv)
+for _vn in [
+    "src_name",
+    "RA",
+    "DEC",
+    "T1",
+    "T2",
+    "Radius",
+    "R_s",
+    "Emin",
+    "Emax",
+    "NEbins",
+    "Efit_min",
+    "Efit_max",
+]:
+    globals()[_vn] = type(globals()[_vn])(inp_pdic[_vn])
 
 E0 = 1.0
 
diff --git a/tools/hess/hess_astro_tool.xml b/tools/hess/hess_astro_tool.xml
index ca2a96a..dff944c 100644
--- a/tools/hess/hess_astro_tool.xml
+++ b/tools/hess/hess_astro_tool.xml
@@ -143,6 +143,10 @@
       </assert_stdout>
     </test>
   </tests>
+  <environment_variables>
+    <environment_variable name="BASEDIR">$__tool_directory__</environment_variable>
+    <environment_variable name="GALAXY_TOOL_DIR">$__tool_directory__</environment_variable>
+  </environment_variables>
   <help>This service provides analysis of publicly available sample &#8220;Data Level
 3&#8221; (DL3) data of HESS gamma-ray telescope, described by `Hess
 Collaboration (2018) &lt;https://arxiv.org/abs/1810.04516&gt;`__. Three types