diff --git a/system/load_configuration.lua b/system/load_configuration.lua
index ef14fe8..5f92076 100644
--- a/system/load_configuration.lua
+++ b/system/load_configuration.lua
@@ -25,6 +25,11 @@ local worldconfig = Settings(worldpath..DIR_DELIM..'_mtimer.conf')
 --   1. Standard `minetest.conf` file that is used for the server
 --   2. `_mtimer.conf` in the loaded world’s directory
 --   3. Provided default value when calling the function
+--
+-- @param key_name The unprefixed name of the key to get
+-- @param default_value What to return when the configuration option is missing
+-- @param changeable If the option is changeable via the config files
+-- @return string Either the configuration option’s value or an empty string
 local set = function (key_name, default_value, changeable)
     local meta_key = 'mtimer:'..key_name
     local config_option = 'mtimer_'..key_name