diff --git a/src/lib_error_monad/error_monad.mli b/src/lib_error_monad/error_monad.mli
index b51894018..1a73f5f46 100644
--- a/src/lib_error_monad/error_monad.mli
+++ b/src/lib_error_monad/error_monad.mli
@@ -71,6 +71,18 @@ type error += Exn of exn
 
 type error += Canceled
 
+(** [protect] is a wrapper around [Lwt.catch] where the error handler operates
+    over `error list` instead of `exn`. Besides, [protect ~on_error ~canceler ~f]
+    may *cancel* [f] via a [Lwt_canceler.t].
+
+    More precisely, [protect ~on_error ~canceler f] runs [f ()]. An Lwt failure
+    triggered by [f ()] is wrapped into an [Exn]. If a [canceler] is given and
+    [Lwt_canceler.cancelation canceler] is determined before [f ()],
+    a [Canceled] error is returned.
+
+    Errors are caught by [~on_error] (if given), otherwise the previous value
+    is returned. An Lwt failure triggered by [~on_error] is wrapped into an
+    [Exn] *)
 val protect :
   ?on_error:(error list -> 'a tzresult Lwt.t) ->
   ?canceler:Lwt_canceler.t ->
diff --git a/src/lib_stdlib/lwt_canceler.mli b/src/lib_stdlib/lwt_canceler.mli
index a1e361bd6..8c23d03ac 100644
--- a/src/lib_stdlib/lwt_canceler.mli
+++ b/src/lib_stdlib/lwt_canceler.mli
@@ -23,9 +23,32 @@
 (*                                                                           *)
 (*****************************************************************************)
 
+(** A [Canceler.t] is a three-states synchronization object with transitions
+    "waiting -> canceling -> canceled", starting in waiting state. A chain
+    of hooks can be attached to the canceler. Hooks are triggered when
+    switching to the canceling state. The canceler switches to canceled state
+    when the hooks have completed. *)
+
 type t
+
+(** [create t] returns a canceler in waiting state. *)
 val create : unit -> t
+
+(** If [t] is in wait state, [cancel t] triggers the cancelation process:
+    1. it switches to canceling state,
+    2. executes the hooks sequentially in separate Lwt threads,
+    3. waits for hooks execution to complete,
+    4. switches to cancel state.
+    If [t] is in canceled state, [cancel t] is determined immediately.
+    If [t] is in canceling state, [cancel t] is determined at the end of the
+    cancelation process. *)
 val cancel : t -> unit Lwt.t
+
+(** [cancelation t] is determined when [t] is in canceling or canceled state. *)
 val cancelation : t -> unit Lwt.t
+
+(** [on_cancel t hook] adds [hook] to the end of the current chain. *)
 val on_cancel : t -> (unit -> unit Lwt.t) -> unit
+
+(** [canceled t] is [true] iff [t] is canceled or canceling. *)
 val canceled : t -> bool
diff --git a/src/lib_stdlib/lwt_utils.mli b/src/lib_stdlib/lwt_utils.mli
index ff124b6bb..437c7da2e 100644
--- a/src/lib_stdlib/lwt_utils.mli
+++ b/src/lib_stdlib/lwt_utils.mli
@@ -27,6 +27,8 @@ val may: f:('a -> unit Lwt.t) -> 'a option -> unit Lwt.t
 
 val never_ending: unit -> 'a Lwt.t
 
+(** [worker name ~run ~cancel] runs worker [run], and logs worker
+    creation, ending or failure. [cancel] is called if worker fails. *)
 val worker:
   string ->
   run:(unit -> unit Lwt.t) ->
@@ -34,8 +36,8 @@ val worker:
   unit Lwt.t
 
 val trigger: unit -> (unit -> unit) * (unit -> unit Lwt.t)
-val sort: ('a -> 'a -> int Lwt.t) -> 'a list -> 'a list Lwt.t
 
+val sort: ('a -> 'a -> int Lwt.t) -> 'a list -> 'a list Lwt.t
 
 val unless: bool -> (unit -> unit Lwt.t) -> unit Lwt.t
 
diff --git a/src/lib_stdlib/lwt_watcher.mli b/src/lib_stdlib/lwt_watcher.mli
index b384b2a20..73c94e0df 100644
--- a/src/lib_stdlib/lwt_watcher.mli
+++ b/src/lib_stdlib/lwt_watcher.mli
@@ -23,14 +23,32 @@
 (*                                                                           *)
 (*****************************************************************************)
 
-(** {1 Notification callbacks} *)
+(** This module implements a one-to-many publish/suscribe pattern.
+
+    Clients can register/unregister to an [input]. Events notified to the input
+    (through [notify]) are dispatched asynchronously to all registered clients
+    through an [Lwt_stream]. A client receives only events sent after
+    registration and before unregistration. *)
 
 type 'a input
-type stopper
 
 val create_input : unit -> 'a input
-val shutdown_input : 'a input -> unit
+
+(** [notify t v] publishes value v to the input t *)
 val notify : 'a input -> 'a -> unit
+
+type stopper
+
+(** [create_stream t] registers a new client which can read published
+    values via a stream. A [stopper] is used to shutdown the client. *)
 val create_stream : 'a input -> 'a Lwt_stream.t * stopper
+
+(** A fake stream never receives any value. *)
 val create_fake_stream : unit -> 'a Lwt_stream.t * stopper
+
+(** [shutdown s] unregisters the client associated to [s]. [None] is pushed
+    to the stream. *)
 val shutdown : stopper -> unit
+
+(** Shutdowns all the clients of this input *)
+val shutdown_input : 'a input -> unit