diff --git a/fs_edit_general.lua b/fs_edit_general.lua
index 9b6b75d..b481a01 100644
--- a/fs_edit_general.lua
+++ b/fs_edit_general.lua
@@ -1,4 +1,78 @@
 
+-- store which player is monitoring the NPC (for preconditions and
+-- effects)
+yl_speak_up.debug_mode_set_by_player = {}
+
+-- for sending debug information about preconditions and effects to
+-- the player who is monitoring the NPC
+-- (sometimes it is not easy/obvious to see why something failed)
+yl_speak_up.debug_msg = function(player, n_id, o_id, text)
+	local dname = yl_speak_up.debug_mode_set_by_player[ n_id ]
+	-- nobody cares
+	if(not(dname)) then
+		return
+	end
+	local pname = player:get_player_name()
+	local d_id = yl_speak_up.speak_to[pname].d_id
+	minetest.chat_send_player(dname, "[NPC "..tostring(n_id)..": "..
+		tostring(pname).."] <"..tostring(d_id).." "..tostring(o_id)..
+		"> "..tostring(text))
+end
+
+
+-- a chat command for entering and leaving debug mode; needs to be a chat command
+-- because the player may have wandered off from his NPC and get too many messages
+-- without a quick way to get rid of them otherwise
+minetest.register_chatcommand( 'npc_talk_debug', {
+	description = "Sets you as debugger for the yl_speak_up-NPC with the ID <n_id>.\n"..
+		"  <list> lists the NPC you are currently debugging.\n"..
+		"  <off> turns debug mode off again.",
+	privs = {npc_talk_owner},
+	func = function(pname, param)
+		if(param and param == "off") then
+			local count = 0
+			for k, v in pairs(yl_speak_up.debug_mode_set_by_player) do
+				if(v and v == pname) then
+					yl_speak_up.debug_mode_set_by_player[ k ] = nil
+					count = count + 1
+					minetest.chat_send_player(pname, "You are no longer "..
+						"debugging the NPC with the ID "..tostring(k)..".")
+				end
+			end
+			minetest.chat_send_player(pname, "Removed you as debugger of "..
+				tostring(count).." NPCs.")
+			return
+		elseif(not(param) or param == "" or param == "list") then
+			local count = 0
+			local text = "You are currently debugging the NPCs with the following IDs:\n"
+			for k, v in pairs(yl_speak_up.debug_mode_set_by_player) do
+				if(v and v == pname) then
+					count = count + 1
+					text = text.."  "..tostring(k)
+				end
+			end
+			if(count == 0) then
+				text = text.." - none -"
+			else
+				text = text.."\nTo turn debugging off, call this command with the "..
+					"parameter <off>."
+			end
+			minetest.chat_send_player(pname, text)
+			return
+		elseif(not(yl_speak_up.may_edit_npc(minetest.get_player_by_name(pname), n_id))) then
+			minetest.chat_send_player(pname, "You do not have the necessary privs to "..
+				"edit that NPC.")
+			return
+		else
+			yl_speak_up.debug_mode_set_by_player[ param ] = pname
+			minetest.chat_send_player(pname, "You are now receiving debug information "..
+				"for NPC "..tostring(param)..".\nTo turn that off, type "..
+				"\"/npc_talk_debug off\".")
+		end
+	end
+});
+
+
 -- evaluate those preconditions of type "function" (set by the staff)
 -- and execute those effects/results of type "function" (set by the staff)
 -- WARNING: This is extremly powerful!
@@ -494,7 +568,7 @@ yl_speak_up.get_fs_edit_option_related = function(player, table_click_result,
 	if(not(x_id)) then
 		x_id = "new"
 	end
-	local save_button = "button[5.0,9.0;1,0.7;save_element;Save]"
+	local save_button = "button[5.0,9.3;1,0.7;save_element;Save]"
 	local formspec =
 		"formspec_version[3]"..
 		"size[20,10]"..
@@ -504,7 +578,11 @@ yl_speak_up.get_fs_edit_option_related = function(player, table_click_result,
 		"dropdown[4.0,1.8;14.0,0.6;select_what;"..
 			table.concat(check_what, ",")..";"..
 			tostring(data.what)..";]"..
-		"button[3.0,9.0;1,0.7;back;Abort]"
+		"label[1,8.5;If you are unsure if your setup of pre(C)onditions and (Ef)fects "..
+			"works as intended,\ntype \"/npc_talk_debug "..tostring(n_id).."\" "..
+			"in chat in order to enter debug mode. You can leave it with "..
+			"\"/npc_talk_debug off\".]"..
+		"button[3.0,9.3;1,0.7;back;Abort]"
 
 	-- "an internal state (i.e. of a quest)", -- 2
 	-- (state is the second offered option in both preconditions and effects list)
diff --git a/fs_edit_preconditions.lua b/fs_edit_preconditions.lua
index d2004b4..e92e5c1 100644
--- a/fs_edit_preconditions.lua
+++ b/fs_edit_preconditions.lua
@@ -198,23 +198,25 @@ end
 --            true (or false).
 yl_speak_up.eval_all_preconditions = function(player, prereq, o_id)
 	if(not(prereq)) then
-minetest.chat_send_player(player:get_player_name(), "No preconditions given for "..tostring(o_id)..".")
+		yl_speak_up.debug_msg(player, n_id, o_id, "No preconditions given.")
 		-- no prerequirements? then they are automaticly fulfilled
 		return true
 	end
 	local pname = player:get_player_name()
-minetest.chat_send_player(pname, "Checking preconditions for "..tostring(o_id).."..") -- TODO
 	local n_id = yl_speak_up.speak_to[pname].n_id
+	yl_speak_up.debug_msg(player, n_id, o_id, "Checking preconditions..")
 	for k, p in pairs(prereq) do
-minetest.chat_send_player(pname, "..checking "..tostring(p.p_id)..": "..yl_speak_up.show_precondition(p)) -- TODO
+		yl_speak_up.debug_msg(player, n_id, o_id, "..checking "..
+			tostring(p.p_id)..": "..yl_speak_up.show_precondition(p))
 		if(not(yl_speak_up.eval_precondition(player, n_id, p))) then
+			yl_speak_up.debug_msg(player, n_id, o_id, tostring(p.p_id)..
+				" -> is false. Aborting.")
 			-- no need to look any further - once we hit a false, it'll stay false
-minetest.chat_send_player(pname, " -> is false! Aborting.") -- TODO
 			return false
 		end
 	end
 	-- all preconditions are true
-minetest.chat_send_player(pname, "All preconditions true for "..tostring(o_id)..".") -- TODO
+	yl_speak_up.debug_msg(player, n_id, o_id, "OK. All preconditions true.")
 	return true
 end