diff --git a/vlib/datatypes/fsm/fsm.v b/vlib/datatypes/fsm/fsm.v
index bb439264a0..43d63b64a4 100644
--- a/vlib/datatypes/fsm/fsm.v
+++ b/vlib/datatypes/fsm/fsm.v
@@ -31,10 +31,12 @@ mut:
 	current_state string
 }
 
+// StateMachine static method returns a new StateMachine instance.
 pub fn new() StateMachine {
 	return StateMachine{}
 }
 
+// set_state sets the current state of the state machine to the given state by `name`.
 pub fn (mut s StateMachine) set_state(name string) ! {
 	if name in s.states {
 		s.current_state = name
@@ -43,10 +45,13 @@ pub fn (mut s StateMachine) set_state(name string) ! {
 	}
 }
 
+// get_state returns the current state of the state machine.
 pub fn (mut s StateMachine) get_state() string {
 	return s.current_state
 }
 
+// add_state adds a new state to the state machine.
+// It takes the `name` of the state, and three event handlers: `entry`, `run`, and `exit`.
 pub fn (mut s StateMachine) add_state(name string, entry EventHandlerFn, run EventHandlerFn, exit EventHandlerFn) {
 	s.states[name] = State{
 		entry_handler: entry
@@ -58,6 +63,8 @@ pub fn (mut s StateMachine) add_state(name string, entry EventHandlerFn, run Eve
 	}
 }
 
+// add_transition adds a new transition to the state machine.
+// It takes the `from` and `to` states, and a condition handler.
 pub fn (mut s StateMachine) add_transition(from string, to string, condition_handler ConditionFn) {
 	t := Transition{
 		to:                to
@@ -70,6 +77,7 @@ pub fn (mut s StateMachine) add_transition(from string, to string, condition_han
 	s.transitions[from] = [t]
 }
 
+// run runs the state machine. It takes a `receiver` argument that is passed to the event handlers.
 pub fn (mut s StateMachine) run(receiver voidptr) ! {
 	from_state := s.current_state
 	mut to_state := s.current_state
diff --git a/vlib/datatypes/fsm/tools/fsm_graph.v b/vlib/datatypes/fsm/tools/fsm_graph.v
index 26368aa526..db516cb8b7 100644
--- a/vlib/datatypes/fsm/tools/fsm_graph.v
+++ b/vlib/datatypes/fsm/tools/fsm_graph.v
@@ -1,6 +1,7 @@
 import os
 import flag
 
+// read_file reads a file and returns the lines as a list of strings. It takes the file path as an argument.
 pub fn read_file(file string) ![]string {
 	if os.is_file(file) {
 		text := os.read_lines(file) or {
@@ -12,6 +13,7 @@ pub fn read_file(file string) ![]string {
 	return ['']
 }
 
+// extract_transitions extracts the transitions from a line and returns it as a formatted string.
 pub fn extract_transitions(line string) ?string {
 	mut result := '  '
 	first_comma := line.index(',')?
@@ -24,12 +26,14 @@ pub fn extract_transitions(line string) ?string {
 	return result + from + ' -> ' + to + ' [label=' + condition + '];'
 }
 
+// get_transitions gets the transitions from a line and returns it as a formatted string using `extract_transitions`.
 pub fn get_transitions(line string) ?string {
 	mut raw_text := line[line.index_any('(') + 1..line.index_any(')')]
 	raw_text = raw_text.replace("'", '').replace(' ', '')
 	return extract_transitions(raw_text)
 }
 
+// main reads a file and generates a graph from the transitions in the file.
 pub fn main() {
 	mut fp := flag.new_flag_parser(os.args)
 	file := fp.string('file', `f`, '', 'input V file with transitions to generate graph from.')