diff --git a/src/terraform_gui.cpp b/src/terraform_gui.cpp
index 632feaf5c6..f644312222 100644
--- a/src/terraform_gui.cpp
+++ b/src/terraform_gui.cpp
@@ -55,7 +55,11 @@ void CcTerraform(Commands, const CommandCost &result, Money, TileIndex tile)
 }
 
 
-/** Scenario editor command that generates desert areas */
+/**
+ * Scenario editor command that generates desert areas.
+ * @param end The end tile of the map drag.
+ * @param start The start tile of the map drag.
+ */
 static void GenerateDesertArea(TileIndex end, TileIndex start)
 {
 	if (_game_mode != GM_EDITOR) return;
@@ -72,7 +76,11 @@ static void GenerateDesertArea(TileIndex end, TileIndex start)
 	InvalidateWindowClassesData(WC_TOWN_VIEW, 0);
 }
 
-/** Scenario editor command that generates rocky areas */
+/**
+ * Scenario editor command that generates rocky areas.
+ * @param end The end tile of the map drag.
+ * @param start The start tile of the map drag.
+ */
 static void GenerateRockyArea(TileIndex end, TileIndex start)
 {
 	if (_game_mode != GM_EDITOR) return;
diff --git a/src/toolbar_gui.cpp b/src/toolbar_gui.cpp
index 316823453a..3379868be2 100644
--- a/src/toolbar_gui.cpp
+++ b/src/toolbar_gui.cpp
@@ -1189,6 +1189,7 @@ static CallBackFunction ToolbarSwitchClick(Window *w)
 
 /**
  * Called when clicking at the date panel of the scenario editor toolbar.
+ * @copydoc ToolbarButtonProc
  */
 static CallBackFunction ToolbarScenDatePanel(Window *w)
 {
@@ -1938,7 +1939,12 @@ class NWidgetScenarioToolbarContainer : public NWidgetToolbarContainer {
 
 /* --- Toolbar handling for the 'normal' case */
 
-typedef CallBackFunction ToolbarButtonProc(Window *w);
+/**
+ * Callback for when a button is clicked in the given window.
+ * @param w The clicked window.
+ * @return The callback function.
+ */
+using ToolbarButtonProc = CallBackFunction(Window *w);
 
 static ToolbarButtonProc * const _toolbar_button_procs[] = {
 	ToolbarPauseClick,
diff --git a/src/town_cmd.cpp b/src/town_cmd.cpp
index 351cfdfe1b..176bd22f90 100644
--- a/src/town_cmd.cpp
+++ b/src/town_cmd.cpp
@@ -170,8 +170,9 @@ Town::~Town()
 /**
  * Invalidating of the "nearest town cache" has to be done
  * after removing item from the pool.
+ * @copydoc Pool::PoolItem::PostDestructor
  */
-void Town::PostDestructor(size_t)
+void Town::PostDestructor([[maybe_unused]] size_t index)
 {
 	InvalidateWindowData(WC_TOWN_DIRECTORY, 0, TDIWD_FORCE_REBUILD);
 	UpdateNearestTownForRoadTiles(false);
@@ -931,6 +932,7 @@ static RoadBits GetTownRoadBits(TileIndex tile)
 /**
  * Get the road type that towns should build at this current moment.
  * They may have built a different type in the past.
+ * @return The best road type for towns at this time.
  */
 RoadType GetTownRoadType()
 {
@@ -1471,6 +1473,7 @@ static bool TownCanGrowRoad(TileIndex tile)
 
 /**
  * Check if the town is allowed to build roads.
+ * @param modes The configuration of the town growth.
  * @return true If the town is allowed to build roads.
  */
 static inline bool TownAllowedToBuildRoads(TownExpandModes modes)
@@ -2698,6 +2701,7 @@ static inline bool TownLayoutAllows2x2HouseHere(Town *t, TileIndex tile, TownExp
  * @param noslope Are foundations disallowed for this house?
  * @param second The diagdir from the first tile to the second tile.
  * @param modes The parts of the town that are being grown.
+ * @return \c true iff a 2x1 or 1x2 house can be built.
  */
 static bool CheckTownBuild2House(TileIndex *tile, Town *t, int maxz, bool noslope, DiagDirection second, TownExpandModes modes)
 {
@@ -2724,6 +2728,7 @@ static bool CheckTownBuild2House(TileIndex *tile, Town *t, int maxz, bool noslop
  * @param maxz The maximum Z level, since all tiles must have the same height.
  * @param noslope Are foundations disallowed for this house?
  * @param modes The parts of the town that are being grown.
+ * @return \c true iff a 2x2 house can be built.
  */
 static bool CheckTownBuild2x2House(TileIndex *tile, Town *t, int maxz, bool noslope, TownExpandModes modes)
 {
diff --git a/src/town_gui.cpp b/src/town_gui.cpp
index 05aab1433e..f64ad6e126 100644
--- a/src/town_gui.cpp
+++ b/src/town_gui.cpp
@@ -529,6 +529,7 @@ public:
 
 	/**
 	 * Gets the desired height for the information panel.
+	 * @param width The width of the panel in pixels.
 	 * @return the desired height in pixels.
 	 */
 	uint GetDesiredInfoHeight(int width) const
diff --git a/src/track_func.h b/src/track_func.h
index 49c81d4764..423cf847a8 100644
--- a/src/track_func.h
+++ b/src/track_func.h
@@ -325,6 +325,7 @@ inline TrackdirBits TrackBitsToTrackdirBits(TrackBits bits)
  * Checks whether a TrackBits has a given Track.
  * @param tracks The track bits.
  * @param track The track to check.
+ * @return \c true iff \c track is in \c tracks.
  */
 inline bool HasTrack(TrackBits tracks, Track track)
 {
@@ -336,6 +337,7 @@ inline bool HasTrack(TrackBits tracks, Track track)
  * Checks whether a TrackdirBits has a given Trackdir.
  * @param trackdirs The trackdir bits.
  * @param trackdir The trackdir to check.
+ * @return \c true iff \c trackdir is in \c trackdirs.
  */
 inline bool HasTrackdir(TrackdirBits trackdirs, Trackdir trackdir)
 {
@@ -494,6 +496,9 @@ inline Trackdir TrackEnterdirToTrackdir(Track track, DiagDirection diagdir)
 /**
  * Maps a track and a full (8-way) direction to the trackdir that represents
  * the track running in the given direction.
+ * @param track The track to get the trackdir for.
+ * @param dir The direction along the track.
+ * @return The resulting trackdir.
  */
 inline Trackdir TrackDirectionToTrackdir(Track track, Direction dir)
 {
diff --git a/src/train_cmd.cpp b/src/train_cmd.cpp
index efccdcade5..0267b872a7 100644
--- a/src/train_cmd.cpp
+++ b/src/train_cmd.cpp
@@ -717,7 +717,10 @@ static CommandCost CmdBuildRailWagon(DoCommandFlags flags, TileIndex tile, const
 	return CommandCost();
 }
 
-/** Move all free vehicles in the depot to the train */
+/**
+ * Move all free vehicles in the depot to the train.
+ * @param u The train to move the free vehicles to.
+ */
 void NormalizeTrainVehInDepot(const Train *u)
 {
 	assert(u->IsEngine());
@@ -2215,7 +2218,6 @@ ClosestDepot Train::FindClosestDepot()
 	return ClosestDepot(tfdd.tile, GetDepotIndex(tfdd.tile), tfdd.reverse);
 }
 
-/** Play a sound for a train leaving the station. */
 void Train::PlayLeaveStationSound(bool force) const
 {
 	static const SoundFx sfx[] = {
@@ -2512,7 +2514,10 @@ static Track DoTrainPathfind(const Train *v, TileIndex tile, DiagDirection enter
 /**
  * Extend a train path as far as possible. Stops on encountering a safe tile,
  * another reservation or a track choice.
- * @return INVALID_TILE indicates that the reservation failed.
+ * @param v The train to extend the reservation for.
+ * @param new_tracks Optional pointer to the track bits at the end of the reservation.
+ * @param enterdir Optional pointer to the enter dir at the end of the reservation.
+ * @return Information about the reservation, empty if no path could be found.
  */
 static PBSTileInfo ExtendTrainReservation(const Train *v, TrackBits *new_tracks, DiagDirection *enterdir)
 {
@@ -3247,6 +3252,7 @@ static uint CheckTrainCollision(Vehicle *v, Train *t)
  * Reports the incident in a flashy news item, modifies station ratings and
  * plays a sound.
  * @param v %Train to test.
+ * @return \c true iff there has been a collision.
  */
 static bool CheckTrainCollision(Train *v)
 {
diff --git a/src/train_gui.cpp b/src/train_gui.cpp
index 5ba28b3340..1968046ae9 100644
--- a/src/train_gui.cpp
+++ b/src/train_gui.cpp
@@ -185,7 +185,11 @@ struct CargoSummaryItem {
 	uint amount;      ///< Amount that is carried
 	StationID source; ///< One of the source stations
 
-	/** Used by std::find() and similar functions */
+	/**
+	 * Used by std::find() and similar functions.
+	 * @param other The other item.
+	 * @return \c true iff both items have the same cargo.
+	 */
 	inline bool operator == (const CargoSummaryItem &other) const
 	{
 		return !(this->cargo != other.cargo);
diff --git a/src/transparency.h b/src/transparency.h
index 8eaa980b71..934f360505 100644
--- a/src/transparency.h
+++ b/src/transparency.h
@@ -46,6 +46,7 @@ extern StationFacilities _facility_display_opt;
  * and if we aren't in the game menu (there's never transparency)
  *
  * @param to the structure which transparency option is ask for
+ * @return \c true if transparency is set for the option, and not in the main menu.
  */
 inline bool IsTransparencySet(TransparencyOption to)
 {
@@ -57,6 +58,7 @@ inline bool IsTransparencySet(TransparencyOption to)
  * and if we aren't in the game menu (there's never transparency)
  *
  * @param to the structure which invisibility option is ask for
+ * @return \c true if invisibility is set for the option, and not in the main menu.
  */
 inline bool IsInvisibilitySet(TransparencyOption to)
 {
diff --git a/src/tree_gui.cpp b/src/tree_gui.cpp
index 23f4d711ee..68fdb13443 100644
--- a/src/tree_gui.cpp
+++ b/src/tree_gui.cpp
@@ -254,7 +254,7 @@ public:
  * Make widgets for the current available tree types.
  * This does not use a NWID_MATRIX or WWT_MATRIX control as those are more difficult to
  * get producing the correct result than dynamically building the widgets is.
- * @see NWidgetFunctionType
+ * @copydoc NWidgetFunctionType
  */
 static std::unique_ptr<NWidgetBase> MakeTreeTypeButtons()
 {
diff --git a/src/vehicle_gui.cpp b/src/vehicle_gui.cpp
index 9f4e5f5274..7e70041d2d 100644
--- a/src/vehicle_gui.cpp
+++ b/src/vehicle_gui.cpp
@@ -567,7 +567,14 @@ void DepotSortList(VehicleList *list)
 	std::sort(list->begin(), list->end(), &VehicleNumberSorter);
 }
 
-/** draw the vehicle profit button in the vehicle list window. */
+/**
+ * Draw the vehicle profit button in the vehicle list window.
+ * @param age The age of the vehicle.
+ * @param display_profit_last_year The profit last year.
+ * @param num_vehicles The number of vehicles in the group.
+ * @param x The X-coordinate to draw the button at.
+ * @param y The Y-coordinate to draw the button at.
+ */
 static void DrawVehicleProfitButton(TimerGameEconomy::Date age, Money display_profit_last_year, uint num_vehicles, int x, int y)
 {
 	SpriteID spr;
@@ -1354,7 +1361,14 @@ void ShowVehicleRefitWindow(const Vehicle *v, VehicleOrderID order, Window *pare
 	w->parent = parent;
 }
 
-/** Display list of cargo types of the engine, for the purchase information window */
+/**
+ * Display list of cargo types of the engine, for the purchase information window.
+ * @param left The left bound of the area to draw in.
+ * @param right The right bound of the area to draw in.
+ * @param y The top bound of the area to draw in.
+ * @param engine The engine to draw the options for.
+ * @return The bottom of the area that was drawn to.
+ */
 uint ShowRefitOptionsList(int left, int right, int y, EngineID engine)
 {
 	/* List of cargo types of this engine */
@@ -1684,7 +1698,14 @@ static void DrawSmallOrderList(const Vehicle *v, int left, int right, int y, uin
 	} while (oid != start);
 }
 
-/** Draw small order list in the vehicle GUI, but without the little black arrow.  This is used for shared order groups. */
+/**
+ * Draw small order list in the vehicle GUI, but without the little black arrow. This is used for shared order groups.
+ * @param orderlist The list of orders to draw.
+ * @param left The left bound of the area to draw in.
+ * @param right The right bound of the area to draw in.
+ * @param y The top bound of the area to draw in.
+ * @param order_arrow_width The width of the order arrow.
+ */
 static void DrawSmallOrderList(const OrderList *orderlist, int left, int right, int y, uint order_arrow_width)
 {
 	if (orderlist == nullptr) return;
@@ -2411,7 +2432,11 @@ struct VehicleDetailsWindow : Window {
 	TrainDetailsWindowTabs tab = TDW_TAB_CARGO; ///< For train vehicles: which tab is displayed.
 	Scrollbar *vscroll = nullptr;
 
-	/** Initialize a newly created vehicle details window */
+	/**
+	 * Initialize a newly created vehicle details window.
+	 * @param desc The configuration of the window.
+	 * @param window_number The unique number of the window within the class.
+	 */
 	VehicleDetailsWindow(WindowDesc &desc, WindowNumber window_number) : Window(desc)
 	{
 		const Vehicle *v = Vehicle::Get(window_number);
@@ -2818,7 +2843,10 @@ static WindowDesc _nontrain_vehicle_details_desc(
 	_nested_nontrain_vehicle_details_widgets
 );
 
-/** Shows the vehicle details window of the given vehicle. */
+/**
+ * Shows the vehicle details window of the given vehicle.
+ * @param v The vehicle to show the window for.
+ */
 static void ShowVehicleDetailsWindow(const Vehicle *v)
 {
 	CloseWindowById(WC_VEHICLE_ORDERS, v->index, false);
@@ -3450,7 +3478,10 @@ static WindowDesc _train_view_desc(
 	&VehicleViewWindow::hotkeys
 );
 
-/** Shows the vehicle view window of the given vehicle. */
+/**
+ * Shows the vehicle view window of the given vehicle.
+ * @param v The vehicle to show the view for.
+ */
 void ShowVehicleViewWindow(const Vehicle *v)
 {
 	AllocateWindowDescFront<VehicleViewWindow>((v->type == VEH_TRAIN) ? _train_view_desc : _vehicle_view_desc, v->index);