diff --git a/src/polyhedron/hooke_polyhedron.cpp b/src/polyhedron/hooke_polyhedron.cpp
index 3a8d1b0..bf222a4 100644
--- a/src/polyhedron/hooke_polyhedron.cpp
+++ b/src/polyhedron/hooke_polyhedron.cpp
@@ -52,21 +52,22 @@ namespace exaDEM
     using ComputeFields = FieldSet< field::_vrot, field::_arot >;
     static constexpr ComputeFields compute_field_set {};
 
-    ADD_SLOT( GridT       , grid              , INPUT_OUTPUT , REQUIRED );
-    ADD_SLOT( GridCellParticleInteraction , ges  , INPUT_OUTPUT , DocString{"Interaction list"} );
-    ADD_SLOT( shapes      , shapes_collection , INPUT_OUTPUT , DocString{"Collection of shapes"});
-    ADD_SLOT( HookeParams , config            , INPUT , REQUIRED ); // can be re-used for to dump contact network
-    ADD_SLOT( HookeParams , config_driver     , INPUT , OPTIONAL ); // can be re-used for to dump contact network
-    ADD_SLOT( mutexes     , locks             , INPUT_OUTPUT );
-    ADD_SLOT( double      , dt                , INPUT , REQUIRED );
-    ADD_SLOT( Drivers     , drivers           , INPUT , DocString{"List of Drivers"});
-		ADD_SLOT( std::vector<size_t> , idxs              , INPUT_OUTPUT , DocString{"List of non empty cells"});
+    ADD_SLOT( GridT       , grid                , INPUT_OUTPUT , REQUIRED );
+    ADD_SLOT( GridCellParticleInteraction , ges , INPUT_OUTPUT , DocString{"Interaction list"} );
+    ADD_SLOT( shapes      , shapes_collection   , INPUT_OUTPUT , DocString{"Collection of shapes"});
+    ADD_SLOT( HookeParams , config              , INPUT , REQUIRED , DocString{"Hooke law parameters used to model interactions sphere/driver"}); // can be re-used for to dump contact network
+    ADD_SLOT( HookeParams , config_driver       , INPUT , OPTIONAL , DocString{"Hooke law parameters used to model interactions sphere/driver"}); // can be re-used for to dump contact network
+    ADD_SLOT( mutexes     , locks               , INPUT_OUTPUT , DocString{"Grid of mutexes, one per particles"});
+    ADD_SLOT( double      , dt                  , INPUT , REQUIRED , DocString{"Timestep"});
+    ADD_SLOT( Drivers     , drivers             , INPUT , DocString{"List of Drivers"});
+		ADD_SLOT( std::vector<size_t> , idxs        , INPUT_OUTPUT , DocString{"List of non empty cells"});
 
 		public:
 
 		inline std::string documentation() const override final
 		{
 			return R"EOF(
+                  Apply Hooke's law between spheres and between spheres with drivers. This operator requires interactions to have been calculated using the nbh_sphere_sym or nbh_spere_no_sym operators.
                 )EOF";
 		}