diff --git a/SPEC.md b/SPEC.md
index 82ce033..4005b41 100644
--- a/SPEC.md
+++ b/SPEC.md
@@ -21,6 +21,13 @@ This document reflects the implementation that ships in this repository today (`
 - **Lists** – `[` begins a list literal, `]` ends it. The compiler captures the intervening stack segment into a freshly `mmap`'d buffer that stores `(len followed by qword items)`, drops the captured values, and pushes the buffer address. Users must `munmap` the buffer when done.
 - **Token customization** – Immediate words can call `add-token` or `add-token-chars` to teach the reader about new multi-character tokens. `fn.sl` uses this in combination with token hooks to recognize `foo(1, 2)` syntax.
 
+### Stack-effect comments
+- **Location and prefix** – Public words in `stdlib/` (and most user code should) document its stack effect with a line comment directly above the definition: `#word_name …`.
+- **Before/after form** – Use `[before] -> [after]`, where each side is a comma-separated list. Items sitting to the left of `|` are deeper in the stack; the segment to the right of `|` runs all the way to the current top-of-stack. Omit the `|` only when a side is empty (`[*]`).
+- **Tail sentinel** – `*` represents the untouched rest of the stack. By convention it is always the first entry on each side so readers can quickly see which values are consumed/produced.
+- **Alternatives** – Separate multiple outcomes with `||`. Each branch repeats the `[before] -> [after]` structure (e.g., `#read_file [*, path | len] -> [*, addr | len] || [*, tag | neg_errno]`).
+- **Examples** – `#dup [* | x] -> [*, x | x]` means a word consumes the top value `x` and returns two copies with the newest copy at TOS; `#arr_pop [* | arr] -> [*, arr | x]` states that the array pointer remains just below the popped element. This notation keeps stack order resonably easy to read and grep.
+
 ## 4. Runtime Model
 - **Stacks** – `r12` holds the data stack pointer, `r13` the return stack pointer. Both live in `.bss` buffers sized by `DSTK_BYTES`/`RSTK_BYTES` (default 64 KiB each). `stdlib/core.sl` implements all standard stack shuffles, arithmetic, comparisons, boolean ops, `@`/`!`, `c@`/`c!`, and return-stack transfers (`>r`, `r>`, `rdrop`, `rpick`).
 - **Calling convention** – Words call each other using the System V ABI. `extern` words marshal arguments into registers before `call symbol`, then push results back onto the data stack. Integer results come from `rax`; floating results come from `xmm0` and are copied into a qword slot.
diff --git a/fn.sl b/fn.sl
index f7b32c4..ebdb140 100644
--- a/fn.sl
+++ b/fn.sl
@@ -1,4 +1,5 @@
-word call-syntax-rewrite            # ( fnameToken -- handled )
+#call-syntax-rewrite [* | fnameToken] -> [* | handled]
+word call-syntax-rewrite
 	dup token-lexeme identifier? 0 == if drop 0 exit end
 	peek-token dup nil? if drop drop 0 exit end
 	dup token-lexeme "(" string= 0 == if drop drop 0 exit end
diff --git a/nob.sl b/nob.sl
index 46a5a80..2c9cbc9 100644
--- a/nob.sl
+++ b/nob.sl
@@ -2,7 +2,7 @@ import stdlib/stdlib.sl
 import stdlib/linux.sl
 import stdlib/mem.sl
 
-# sh ( cmd_addr cmd_len -- exit_code | neg_errno )
+# sh  [*, cmd_addr | cmd_len ] -> [* | exit_code ]
 word sh
     swap
     >r                       # save cmd_addr
diff --git a/stdlib/arr.sl b/stdlib/arr.sl
index 3345fe3..c33432c 100644
--- a/stdlib/arr.sl
+++ b/stdlib/arr.sl
@@ -11,7 +11,7 @@
 
 import mem.sl
 
-# : arr_new ( cap -- arr )
+#arr_new [* | cap] -> [* | arr]
 # Create a new array with given initial capacity (minimum 1)
 word arr_new
     dup 1 < if drop 1 end
@@ -22,21 +22,21 @@ word arr_new
     nip
 end
 
-# : arr_len ( arr -- len )
+#arr_len [* | arr] -> [* | len]
 word arr_len @ end
 
-# : arr_cap ( arr -- cap )
+#arr_cap [* | arr] -> [* | cap]
 word arr_cap 8 + @ end
 
-# : arr_data ( arr -- ptr )
+#arr_data [* | arr] -> [* | ptr]
 word arr_data 16 + @ end
 
-# : arr_free ( arr -- )
+#arr_free [* | arr] -> [*]
 word arr_free
     dup arr_cap 8 * 24 + free
 end
 
-# Helper: copy n qwords from src to dst (dst src n --)
+# Helper: copy n qwords from src to dst [*, dst, src | n] -> [*]
 word arr_copy_elements
     while dup 0 > do
         over @ 3 pick swap !   # dst = *src
@@ -47,7 +47,7 @@ word arr_copy_elements
     drop 2drop
 end
 
-# : arr_reserve ( cap arr -- arr )
+#arr_reserve [*, cap | arr] -> [* | arr]
 # Ensures capacity >= cap; returns (possibly moved) arr pointer.
 word arr_reserve
     swap dup 1 < if drop 1 end swap   # reqcap arr
@@ -77,7 +77,7 @@ word arr_reserve
     end
 end
 
-# : arr_push ( x arr -- arr )
+#arr_push [*, x | arr] -> [* | arr]
 # Push element onto array, growing if needed
 word arr_push
     dup arr_len over arr_cap >= if
@@ -94,27 +94,26 @@ word arr_push
     dup @ 1 + over swap !
 end
 
-# : arr_pop ( arr -- x arr )
+#arr_pop [* | arr] -> [*, arr | x]
 # Pop element from array (returns 0 if empty)
 word arr_pop
     dup arr_len 0 == if
-        0 swap
+        0
     else
         # Decrement len
         dup @ 1 - over swap !
         # Get element at new len position
         dup arr_data over arr_len 8 * + @
-        swap
     end
 end
 
-# : arr_get ( i arr -- x )
+#arr_get [*, i | arr] -> [* | x]
 # Get element at index i
 word arr_get
     arr_data swap 8 * + @
 end
 
-# : arr_set ( x i arr -- )
+#arr_set [*, x, i | arr] -> [*]
 # Set element at index i to x
 word arr_set
     arr_data swap 8 * + swap !
diff --git a/stdlib/arr_asm.sl b/stdlib/arr_asm.sl
index 48c7327..acd5f71 100644
--- a/stdlib/arr_asm.sl
+++ b/stdlib/arr_asm.sl
@@ -9,7 +9,7 @@
 # Allocation: mmap; free: munmap.
 # Growth: allocate new block, copy elements, munmap old block.
 
-# : arr_new ( cap -- arr )
+#arr_new [* | cap] -> [* | arr]
 :asm arr_new {
 	mov r14, [r12]        ; requested cap
 	cmp r14, 1
@@ -42,7 +42,7 @@
 }
 ;
 
-# : arr_len ( arr -- len )
+#arr_len [* | arr] -> [* | len]
 :asm arr_len {
 	mov rax, [r12]
 	mov rax, [rax]
@@ -51,7 +51,7 @@
 }
 ;
 
-# : arr_cap ( arr -- cap )
+#arr_cap [* | arr] -> [* | cap]
 :asm arr_cap {
 	mov rax, [r12]
 	mov rax, [rax + 8]
@@ -60,7 +60,7 @@
 }
 ;
 
-# : arr_data ( arr -- ptr )
+#arr_data [* | arr] -> [* | ptr]
 :asm arr_data {
 	mov rax, [r12]
 	mov rax, [rax + 16]
@@ -69,7 +69,7 @@
 }
 ;
 
-# : arr_free ( arr -- )
+#arr_free [* | arr] -> [*]
 :asm arr_free {
 	mov rbx, [r12]        ; base
 	mov rcx, [rbx + 8]    ; cap
@@ -84,7 +84,7 @@
 }
 ;
 
-# : arr_reserve ( cap arr -- arr )
+#arr_reserve [*, cap | arr] -> [* | arr]
 # Ensures capacity >= cap; returns (possibly moved) arr pointer.
 :asm arr_reserve {
 	mov rbx, [r12]        ; arr
@@ -151,7 +151,7 @@
 }
 ;
 
-# : arr_push ( x arr -- arr )
+#arr_push [*, x | arr] -> [* | arr]
 :asm arr_push {
 	mov rbx, [r12]        ; arr
 	mov rcx, [rbx]        ; len
@@ -227,7 +227,7 @@
 }
 ;
 
-# : arr_pop ( arr -- x arr )
+#arr_pop [* | arr] -> [*, arr | x]
 :asm arr_pop {
 	mov rbx, [r12]        ; arr
 	mov rcx, [rbx]        ; len
@@ -245,4 +245,4 @@
 	mov [r12], rax
 	ret
 }
-;
\ No newline at end of file
+;
diff --git a/stdlib/core.sl b/stdlib/core.sl
index 356c734..9728df0 100644
--- a/stdlib/core.sl
+++ b/stdlib/core.sl
@@ -2,6 +2,7 @@
 # persistent: resb 64
 # push the addr of it
 
+#mem [*] -> [* | ptr]
 :asm mem {
 	lea rax, [rel persistent]
 	sub r12, 8
@@ -9,7 +10,7 @@
 }
 ;
 
-# : argc ( -- n )
+#argc [*] -> [* | n]
 :asm argc {
 	extern sys_argc
 	mov rax, [rel sys_argc]
@@ -19,7 +20,7 @@
 }
 ;
 
-# : argv ( -- ptr )
+#argv [*] -> [* | ptr]
 :asm argv {
 	extern sys_argv
 	mov rax, [rel sys_argv]
@@ -29,7 +30,7 @@
 }
 ;
 
-# : argv@ ( n -- ptr )
+#argv@ [* | n] -> [* | ptr]
 :asm argv@ {
 	extern sys_argv
 	mov rbx, [r12]      ; n
@@ -40,7 +41,7 @@
 }
 ;
 
-# : c@ ( addr -- byte )
+#c@ [* | addr] -> [* | byte]
 :asm c@ {
 	mov rax, [r12]         ; get address from stack
 	movzx rax, byte [rax]  ; load byte at address, zero-extend to rax
@@ -49,7 +50,7 @@
 }
 ;
 
-# : c! ( byte addr -- )
+#c! [*, byte | addr] -> [*]
 :asm c! {
 	mov rax, [r12]         ; get address from stack
 	add r12, 8             ; pop address
@@ -60,7 +61,7 @@
 }
 ;
 
-# : r@ ( -- x )
+#r@ [*] -> [* | x]
 :asm r@ {
 	mov rax, [r13]         ; get value from return stack
 	sub r12, 8             ; make room on data stack
@@ -69,7 +70,7 @@
 }
 ;
 
-# : dup ( x -- x x )
+#dup [* | x] -> [*, x | x]
 :asm dup {
 	mov rax, [r12]         ; get top of stack
 	sub r12, 8             ; make room
@@ -77,13 +78,13 @@
 }
 ;
 
-# : drop ( x -- )
+#drop [* | x] -> [*]
 :asm drop {
 	add r12, 8             ; remove top of stack
 }
 ;
 
-# : over ( x1 x2 -- x1 x2 x1 )
+#over [*, x1 | x2] -> [*, x1, x2 | x1]
 :asm over {
 	mov rax, [r12 + 8]     ; get second item
 	sub r12, 8              ; make room
@@ -91,7 +92,7 @@
 }
 ;
 
-# : swap ( x1 x2 -- x2 x1 )
+#swap [*, x1 | x2] -> [*, x2 | x1]
 :asm swap {
 	mov rax, [r12]         ; get top
 	mov rbx, [r12 + 8]     ; get second
@@ -100,7 +101,7 @@
 }
 ;
 
-# : rot ( x1 x2 x3 -- x2 x3 x1 )
+#rot [*, x1, x2 | x3] -> [*, x2, x3 | x1]
 :asm rot {
 	mov rax, [r12]         ; x3 (top)
 	mov rbx, [r12 + 8]     ; x2
@@ -111,7 +112,7 @@
 }
 ;
 
-# : -rot ( x1 x2 x3 -- x3 x1 x2 )
+#-rot [*, x1, x2 | x3] -> [*, x3, x1 | x2]
 :asm -rot {
 	mov rax, [r12]         ; x3 (top)
 	mov rbx, [r12 + 8]     ; x2
@@ -122,7 +123,7 @@
 }
 ;
 
-# : nip ( x1 x2 -- x2 )
+#nip [*, x1 | x2] -> [* | x2]
 :asm nip {
 	mov rax, [r12]         ; get top
 	add r12, 8             ; drop lower
@@ -130,7 +131,7 @@
 }
 ;
 
-# : tuck ( x1 x2 -- x2 x1 x2 )
+#tuck [*, x1 | x2] -> [*, x2, x1 | x2]
 :asm tuck {
 	mov rax, [r12]         ; x2 (top)
 	mov rbx, [r12 + 8]     ; x1
@@ -141,7 +142,7 @@
 }
 ;
 
-# : 2dup ( x1 x2 -- x1 x2 x1 x2 )
+#2dup [*, x1 | x2] -> [*, x1, x2, x1 | x2]
 :asm 2dup {
 	mov rax, [r12]         ; b (top)
 	mov rbx, [r12 + 8]     ; a
@@ -152,13 +153,13 @@
 }
 ;
 
-# : 2drop ( x1 x2 -- )
+#2drop [*, x1 | x2] -> [*]
 :asm 2drop {
 	add r12, 16            ; remove two items
 }
 ;
 
-# : 2swap ( x1 x2 x3 x4 -- x3 x4 x1 x2 )
+#2swap [*, x1, x2, x3 | x4] -> [*, x3, x4, x1 | x2]
 :asm 2swap {
 	mov rax, [r12]         ; d (top)
 	mov rbx, [r12 + 8]     ; c
@@ -171,7 +172,7 @@
 }
 ;
 
-# : 2over ( x1 x2 x3 x4 -- x3 x4 x1 x2 x3 x4 )
+#2over [*, x1, x2, x3 | x4] -> [*, x3, x4, x1, x2, x3 | x4]
 :asm 2over {
 	mov rax, [r12 + 16]    ; b
 	mov rbx, [r12 + 24]    ; a
@@ -182,7 +183,7 @@
 }
 ;
 
-# : + ( x1 x2 -- x3 )
+#+ [*, x1 | x2] -> [* | x3]
 :asm + {
 	mov rax, [r12]         ; get top
 	add r12, 8             ; pop
@@ -190,7 +191,7 @@
 }
 ;
 
-# : - ( x1 x2 -- x3 )
+#- [*, x1 | x2] -> [* | x3]
 :asm - {
 	mov rax, [r12]         ; get top
 	add r12, 8             ; pop
@@ -198,7 +199,7 @@
 }
 ;
 
-# : * ( x1 x2 -- x3 )
+#* [*, x1 | x2] -> [* | x3]
 :asm * {
 	mov rax, [r12]         ; get top
 	add r12, 8             ; pop
@@ -207,7 +208,7 @@
 }
 ;
 
-# : / ( x1 x2 -- x3 )
+#/ [*, x1 | x2] -> [* | x3]
 :asm / {
 	mov rbx, [r12]         ; divisor
 	add r12, 8             ; pop
@@ -218,7 +219,7 @@
 }
 ;
 
-# : % ( x1 x2 -- x3 )
+#% [*, x1 | x2] -> [* | x3]
 :asm % {
 	mov rbx, [r12]         ; divisor
 	add r12, 8             ; pop
@@ -229,7 +230,7 @@
 }
 ;
 
-# : == ( x1 x2 -- flag )
+#== [*, x1 | x2] -> [* | flag]
 :asm == {
 	mov rax, [r12]         ; get top
 	add r12, 8             ; pop
@@ -241,7 +242,7 @@
 }
 ;
 
-# : != ( x1 x2 -- flag )
+#!= [*, x1 | x2] -> [* | flag]
 :asm != {
 	mov rax, [r12]         ; get top
 	add r12, 8             ; pop
@@ -253,7 +254,7 @@
 }
 ;
 
-# : < ( x1 x2 -- flag )
+#< [*, x1 | x2] -> [* | flag]
 :asm < {
 	mov rax, [r12]         ; get top
 	add r12, 8             ; pop
@@ -265,7 +266,7 @@
 }
 ;
 
-# : > ( x1 x2 -- flag )
+#> [*, x1 | x2] -> [* | flag]
 :asm > {
 	mov rax, [r12]         ; get top
 	add r12, 8             ; pop
@@ -277,7 +278,7 @@
 }
 ;
 
-# : <= ( x1 x2 -- flag )
+#<= [*, x1 | x2] -> [* | flag]
 :asm <= {
 	mov rax, [r12]         ; get top
 	add r12, 8             ; pop
@@ -289,7 +290,7 @@
 }
 ;
 
-# : >= ( x1 x2 -- flag )
+#>= [*, x1 | x2] -> [* | flag]
 :asm >= {
 	mov rax, [r12]         ; get top
 	add r12, 8             ; pop
@@ -301,7 +302,7 @@
 }
 ;
 
-# : @ ( addr -- x )
+#@ [* | addr] -> [* | x]
 :asm @ {
 	mov rax, [r12]         ; get address
 	mov rax, [rax]         ; load value
@@ -309,7 +310,7 @@
 }
 ;
 
-# : ! ( x addr -- )
+#! [*, x | addr] -> [*]
 :asm ! {
 	mov rax, [r12]         ; get value (TOS)
 	add r12, 8             ; pop value
@@ -319,7 +320,7 @@
 }
 ;
 
-# : mmap ( addr len prot flags fd offset -- addr )
+#mmap [*, addr, len, prot, flags, fd | offset] -> [* | addr]
 :asm mmap {
 	mov r9, [r12]          ; offset
 	add r12, 8
@@ -339,7 +340,7 @@
 }
 ;
 
-# : munmap ( addr len -- res )
+#munmap [*, addr | len] -> [* | res]
 :asm munmap {
 	mov rsi, [r12]         ; len
 	add r12, 8
@@ -352,7 +353,7 @@
 }
 ;
 
-# : exit ( code -- )
+#exit [* | code] -> [*]
 :asm exit {
 	mov rdi, [r12]         ; exit code
 	add r12, 8
@@ -361,7 +362,7 @@
 }
 ;
 
-# : and ( x1 x2 -- flag )
+#and [*, x1 | x2] -> [* | flag]
 :asm and {
 	mov rax, [r12]         ; get top
 	add r12, 8             ; pop
@@ -377,7 +378,7 @@
 }
 ;
 
-# : or ( x1 x2 -- flag )
+#or [*, x1 | x2] -> [* | flag]
 :asm or {
 	mov rax, [r12]         ; get top
 	add r12, 8             ; pop
@@ -393,7 +394,7 @@
 }
 ;
 
-# : not ( x -- flag )
+#not [* | x] -> [* | flag]
 :asm not {
 	mov rax, [r12]         ; get value
 	test rax, rax
@@ -403,7 +404,7 @@
 }
 ;
 
-# : >r ( x -- )
+#>r [* | x] -> [*]
 :asm >r {
 	mov rax, [r12]         ; get value
 	add r12, 8             ; pop
@@ -412,7 +413,7 @@
 }
 ;
 
-# : r> ( -- x )
+#r> [*] -> [* | x]
 :asm r> {
 	mov rax, [r13]         ; get value from return stack
 	add r13, 8             ; pop return stack
@@ -421,13 +422,13 @@
 }
 ;
 
-# : rdrop ( -- )
+#rdrop [*] -> [*]
 :asm rdrop {
 	add r13, 8             ; pop return stack
 }
 ;
 
-# : pick ( n -- x )
+#pick [* | n] -> [* | x]
 :asm pick {
 	mov rcx, [r12]         ; get index
 	add r12, 8             ; pop
@@ -437,7 +438,7 @@
 }
 ;
 
-# : rpick ( n -- x )
+#rpick [* | n] -> [* | x]
 :asm rpick {
 	mov rcx, [r12]         ; get index
 	add r12, 8             ; pop
@@ -447,7 +448,7 @@
 }
 ;
 
-# : neg ( x -- -x )
+#neg [* | x] -> [* | -x]
 :asm neg {
     mov rax, [r12]   ; get value
     neg rax          ; arithmetic negation
@@ -455,7 +456,7 @@
 }
 ;
 
-# : abs ( x -- |x| )
+#abs [* | x] -> [* | |x|]
 :asm abs {
 	mov rax, [r12]   ; get value
 	test rax, rax    ; check sign
@@ -466,7 +467,7 @@
 }
 ;
 
-# : bitnot ( 0|1 -- 1|0 )
+#bitnot [* | bool] -> [* | bool]
 :asm bitnot {
     mov rax, [r12]   ; get value
     xor rax, 1       ; flip lowest bit
@@ -474,7 +475,7 @@
 }
 ;
 
-# : band ( x1 x2 -- x3 )
+#band [*, x1 | x2] -> [* | x3]
 :asm band {
 	mov rax, [r12]         ; get top
 	add r12, 8             ; pop
@@ -482,7 +483,7 @@
 }
 ;
 
-# : bor ( x1 x2 -- x3 )
+#bor [*, x1 | x2] -> [* | x3]
 :asm bor {
 	mov rax, [r12]         ; get top
 	add r12, 8             ; pop
@@ -490,7 +491,7 @@
 }
 ;
 
-# : bxor ( x1 x2 -- x3 )
+#bxor [*, x1 | x2] -> [* | x3]
 :asm bxor {
 	mov rax, [r12]         ; get top
 	add r12, 8             ; pop
@@ -498,13 +499,13 @@
 }
 ;
 
-# : bnot ( x -- x )
+#bnot [* | x] -> [* | x]
 :asm bnot {
 	not qword [r12]        ; bitwise not
 }
 ;
 
-# : shl ( x1 x2 -- x3 )
+#shl [*, x1 | x2] -> [* | x3]
 :asm shl {
 	mov rcx, [r12]         ; shift count
 	add r12, 8             ; pop
@@ -512,7 +513,7 @@
 }
 ;
 
-# : sal ( x1 x2 -- x3 )
+#sal [*, x1 | x2] -> [* | x3]
 :asm sal {
 	mov rcx, [r12]         ; shift count
 	add r12, 8             ; pop
@@ -520,7 +521,7 @@
 }
 ;
 
-# : shr ( x1 x2 -- x3 )
+#shr [*, x1 | x2] -> [* | x3]
 :asm shr {
 	mov rcx, [r12]         ; shift count
 	add r12, 8             ; pop
@@ -528,7 +529,7 @@
 }
 ;
 
-# : sar ( x1 x2 -- x3 )
+#sar [*, x1 | x2] -> [* | x3]
 :asm sar {
 	mov rcx, [r12]         ; shift count
 	add r12, 8             ; pop
@@ -536,7 +537,7 @@
 }
 ;
 
-# : rol ( x1 x2 -- x3 )
+#rol [*, x1 | x2] -> [* | x3]
 :asm rol {
 	mov rcx, [r12]         ; shift count
 	add r12, 8             ; pop
@@ -544,7 +545,7 @@
 }
 ;
 
-# : ror ( x1 x2 -- x3 )
+#ror [*, x1 | x2] -> [* | x3]
 :asm ror {
 	mov rcx, [r12]         ; shift count
 	add r12, 8             ; pop
@@ -552,19 +553,19 @@
 }
 ;
 
-# : inc ( x -- x+1 )
+#inc [* | x] -> [* | x+1]
 :asm inc {
 	inc qword [r12]
 }
 ;
 
-# : dec ( x -- x-1 )
+#dec [* | x] -> [* | x-1]
 :asm dec {
 	dec qword [r12]
 }
 ;
 
-# : min ( x1 x2 -- x3 )
+#min [*, x1 | x2] -> [* | x3]
 :asm min {
 	mov rax, [r12]         ; x2
 	add r12, 8             ; pop
@@ -575,7 +576,7 @@
 }
 ;
 
-# : max ( x1 x2 -- x3 )
+#max [*, x1 | x2] -> [* | x3]
 :asm max {
 	mov rax, [r12]         ; x2
 	add r12, 8             ; pop
@@ -586,7 +587,7 @@
 }
 ;
 
-# : clamp ( x lo hi -- y )
+#clamp [*, x, lo | hi] -> [* | y]
 :asm clamp {
 	mov rax, [r12]         ; hi
 	mov rbx, [r12 + 8]     ; lo
@@ -600,7 +601,7 @@
 }
 ;
 
-# : time ( -- t )
+#time [*] -> [* | t]
 :asm time {
 	mov rax, 201           ; syscall: time
 	xor rdi, rdi
@@ -611,7 +612,7 @@
 }
 ;
 
-# : rand ( -- n )
+#rand [*] -> [* | n]
 :asm rand {
 	lea rbx, [rel persistent]
 	mov rax, [rbx]         ; state
diff --git a/stdlib/debug.sl b/stdlib/debug.sl
index 4a3009f..6922374 100644
--- a/stdlib/debug.sl
+++ b/stdlib/debug.sl
@@ -1,7 +1,7 @@
 import stdlib.sl
 import io.sl
 
-# : dump ( n -- )
+#dump [* | n] -> [*]
 
 # dump takes the firts element from the stack
 # and prints that much consequent elements
@@ -28,7 +28,7 @@ word rdump
 	drop
 end
 
-# : int3 ( -- )
+#int3 [*] -> [*]
 :asm int3 {
 	int3
 }
diff --git a/stdlib/io.sl b/stdlib/io.sl
index fd77c09..4da4dce 100644
--- a/stdlib/io.sl
+++ b/stdlib/io.sl
@@ -1,8 +1,8 @@
 # L2 IO Primitives
 
-# : read_file ( path_addr path_len -- addr len | 0 0 )
+#read_file [*, path_addr | path_len] -> [*, addr | len] || [*, tag | neg_errno]
 #   Reads the file at the given path (pointer+length, not null-terminated),
-#   returns (addr len) of mapped file, or (0 0) on error.
+#   returns (addr len) of mapped file, or (tag neg_errno) on error.
 
 :asm read_file {
 	; stack: path_addr (NOS), path_len (TOS)
@@ -79,7 +79,7 @@
 }
 ;
 
-# : write_file ( path_ptr path_len buf_ptr buf_len -- bytes_written | neg_errno )
+#write_file [*, path_ptr, path_len, buf_ptr | buf_len] -> [* | bytes_written] || [* | neg_errno]
 :asm write_file {
 	; stack: path_addr, path_len, buf_addr, buf_len (TOS)
 	mov r13, [r12]        ; buf_len
@@ -132,7 +132,7 @@
 }
 ;
 
-# : read_stdin ( max_len -- addr len | neg_errno 0 )
+#read_stdin [* | max_len] -> [*, addr | len] || [*, tag | neg_errno]
 :asm read_stdin {
 	; stack: max_len
 	mov r14, [r12]        ; max_len
@@ -268,7 +268,7 @@
 }
 ;
 
-# : write_buf ( addr len -- )
+#write_buf [*, addr | len] -> [*]
 :asm write_buf (effects string-io) {
 	mov rdx, [r12]        ; len
 	mov rsi, [r12 + 8]    ; addr
@@ -280,7 +280,7 @@
 }
 ;
 
-# : ewrite_buf ( addr len -- )
+#ewrite_buf [*, addr | len] -> [*]
 :asm ewrite_buf (effects string-io) {
 	mov rdx, [r12]        ; len
 	mov rsi, [r12 + 8]    ; addr
@@ -292,7 +292,7 @@
 }
 ;
 
-# : putc ( char -- )
+#putc [* | char] -> [*]
 :asm putc {
 	mov rax, [r12]
 	add r12, 8
@@ -306,7 +306,7 @@
 }
 ;
 
-# : puti ( int -- )
+#puti [* | int] -> [*]
 :asm puti {
 	mov rax, [r12]      ; get int
 	add r12, 8          ; pop
diff --git a/stdlib/linux.sl b/stdlib/linux.sl
index 8601122..98badc2 100644
--- a/stdlib/linux.sl
+++ b/stdlib/linux.sl
@@ -2,7 +2,7 @@
 # Provides syscall constants and helpers for L2 programs
 
 # swap impl is provided so this can be used without the need for stdlib
-# : ___linux_swap ( x1 x2 -- x2 x1 )
+#___linux_swap [*, x1 | x2] -> [*, x2 | x1]
 :asm ___linux_swap {
 	mov rax, [r12]         ; get top
 	mov rbx, [r12 + 8]     ; get second
diff --git a/stdlib/mem.sl b/stdlib/mem.sl
index 9091258..05a1b88 100644
--- a/stdlib/mem.sl
+++ b/stdlib/mem.sl
@@ -1,5 +1,6 @@
 import stdlib.sl
 
+#alloc [* | size] -> [* | addr]
 word alloc
     0      # addr hint (NULL)
     swap   # size
@@ -11,11 +12,13 @@ word alloc
     swap drop
 end
 
+#free [*, addr | size] -> [*]
 word free
     munmap drop
 end
 
-word memcpy #(dst_addr src_addr len -- dst_addr len)
+#memcpy [*, dst_addr, src_addr | len] -> [*, dst_addr | len]
+word memcpy
     dup
     >r
     swap
@@ -40,7 +43,8 @@ word memcpy #(dst_addr src_addr len -- dst_addr len)
     r> dup -rot - swap
 end
 
-word memset #( value len addr -- )
+#memset [*, value, len | addr] -> [*]
+word memset
     swap
     0 swap for
         -rot swap 2 pick + 2dup swap ! 1 + -rot swap
@@ -48,15 +52,17 @@ word memset #( value len addr -- )
     2drop drop
 end
 
-word memdump #( len addr -- addr )
+#memdump [*, len | addr] -> [* | addr]
+word memdump
     for
         dup c@ puti cr 1 +
     end
 end
 
-word realloc #( addr old_len new_len -- new_addr )
+#realloc [*, addr, old_len | new_len] -> [* | new_addr]
+word realloc
     2 pick swap alloc
     rot rot swap
     memcpy
     swap -rot free
-end
\ No newline at end of file
+end
diff --git a/stdlib/utils.sl b/stdlib/utils.sl
index 1f5a256..3d2a8fb 100644
--- a/stdlib/utils.sl
+++ b/stdlib/utils.sl
@@ -1,10 +1,10 @@
 
-# : strcmp ( addr len addr len -- bool addr len addr len)
+#strcmp [*, addr, len, addr | len] -> [*, addr, len, addr, len | bool]
 word strcmp
     3 pick 2 pick @ swap @ ==
 end
 
-# : strconcat ( addr len addr len -- addr len)
+#strconcat [*, addr, len, addr | len] -> [*, addr | len]
 word strconcat
     0 pick 3 pick +
     dup
@@ -31,7 +31,7 @@ word strconcat
     rdrop rdrop rdrop
 end
 
-# : strlen ( addr -- len )
+#strlen [* | addr] -> [* | len]
 # for null terminated strings
 word strlen
     0 swap                  # len addr
@@ -42,7 +42,8 @@ word strlen
     drop                    # drop addr, leave len
 end
 
-word digitsN>num  # ( d_{n-1} ... d0 n -- value ), digits bottom=MSD, top=LSD, length on top (MSD-most significant digit, LSD-least significant digit)
+#digitsN>num [*, d_{n-1}, d0 | n] -> [* | value]
+word digitsN>num  # digits bottom=MSD, top=LSD, length on top (MSD-most significant digit, LSD-least significant digit)
     0 swap        # place accumulator below length
     for           # loop n times using the length on top
         r@ pick   # fetch next digit starting from MSD (uses loop counter as index)
@@ -52,7 +53,8 @@ word digitsN>num  # ( d_{n-1} ... d0 n -- value ), digits bottom=MSD, top=LSD, l
     end
 end
 
-# : toint (addr len -- int ) converts a string to an int
+#toint [*, addr | len] -> [* | int]
+# converts a string to an int
 word toint
     swap
     over 0 swap
@@ -75,7 +77,8 @@ word toint
     rdrop rdrop
 end
 
-# : count_digits ( int -- int) returns the amount of digits of an int
+#count_digits [* | int] -> [* | int]
+# returns the amount of digits of an int
 word count_digits
     0
     swap
@@ -85,7 +88,8 @@ word count_digits
     drop
 end
 
-# : tostr ( int -- addr len ) the function allocates a buffer to remember to free it
+#tostr [* | int] -> [*, addr | len]
+# the function allocates a buffer, remember to free it
 word tostr
     dup
     count_digits
@@ -115,4 +119,4 @@ word tostr
     over for
     rot drop
     end drop
-end
\ No newline at end of file
+end