diff --git a/src/lib_shell/mempool_peer_worker.ml b/src/lib_shell/mempool_peer_worker.ml
index 6273bdbf8..3aad729fd 100644
--- a/src/lib_shell/mempool_peer_worker.ml
+++ b/src/lib_shell/mempool_peer_worker.ml
@@ -36,7 +36,7 @@ module type T = sig
   type t
   type input = Operation_hash.t list
 
-  val create: limits -> P2p_peer.Id.t -> Mempool_worker.t -> input -> t Lwt.t
+  val create: limits -> P2p_peer.Id.t -> Mempool_worker.t -> t Lwt.t
   val shutdown: t -> input Lwt.t
 
   val validate: Mempool_worker.t -> t -> input -> unit tzresult Lwt.t
@@ -62,6 +62,29 @@ module Make (Mempool_worker: Mempool_worker.T)
   type output = result Operation_hash.Map.t
 
   let pp_input = Format.pp_print_list Operation_hash.pp
+  let result_encoding =
+    let open Data_encoding in
+    union
+      [ case (Tag 0)
+          ~title:"Cannot download"
+          (obj1 (req "download_errors" (list Error_monad.error_encoding)))
+          (function Cannot_download errs -> Some errs | _ -> None)
+          (fun errs -> Cannot_download errs) ;
+        case (Tag 1)
+          ~title:"Cannot parse"
+          (obj1 (req "parse_errors" (list Error_monad.error_encoding)))
+          (function Cannot_parse errs -> Some errs | _ -> None)
+          (fun errs -> Cannot_parse errs) ;
+        case (Tag 2)
+          ~title:"Cannot validate"
+          (obj1 (req "validation_errors" (list Error_monad.error_encoding)))
+          (function Cannot_validate errs -> Some errs | _ -> None)
+          (fun errs -> Cannot_validate errs) ;
+        case (Tag 3)
+          ~title:"Validation result"
+          (obj1 (req "validation_result" Mempool_worker.result_encoding))
+          (function Mempool_result result -> Some result | _ -> None)
+          (fun result -> Mempool_result result) ]
 
   module Log = Tezos_stdlib.Logging.Make(struct
       let name = "node.mempool.peer_worker"
@@ -76,7 +99,6 @@ module Make (Mempool_worker: Mempool_worker.T)
     type t = {
       received: Operation_hash.t Queue.t;
       downloading: (Operation_hash.t * Operation.t tzresult Lwt.t) Queue.t;
-      parsing: (Operation_hash.t * Mempool_worker.operation tzresult Lwt.t) Queue.t;
       applying: (Mempool_worker.operation * Mempool_worker.result tzresult Lwt.t) Queue.t;
       mutable results: result Operation_hash.Map.t
     }
@@ -86,7 +108,6 @@ module Make (Mempool_worker: Mempool_worker.T)
     let is_empty t =
       Queue.is_empty t.received &&
       Queue.is_empty t.downloading &&
-      Queue.is_empty t.parsing &&
       Queue.is_empty t.applying
 
     let has_resolved t = match Lwt.state t with
@@ -108,7 +129,6 @@ module Make (Mempool_worker: Mempool_worker.T)
       in
       Lwt.choose (
         (first_task_or_never t.downloading) ::
-        (first_task_or_never t.parsing) ::
         (first_task_or_never t.applying) ::
         []
       )
@@ -125,7 +145,6 @@ module Make (Mempool_worker: Mempool_worker.T)
       {
         received = q_of_list op_hashes;
         downloading = Queue.create ();
-        parsing = Queue.create ();
         applying = Queue.create ();
         results = Operation_hash.Map.empty;
       }
@@ -133,7 +152,6 @@ module Make (Mempool_worker: Mempool_worker.T)
     let cancel pipeline =
       let cancel_snd (_, p) = Lwt.cancel p in
       Queue.iter cancel_snd pipeline.downloading;
-      Queue.iter cancel_snd pipeline.parsing;
       Queue.iter cancel_snd pipeline.applying
 
 
@@ -156,18 +174,6 @@ module Make (Mempool_worker: Mempool_worker.T)
             Lwt.return_unit
       end
 
-      else if head_is_resolved pipeline.parsing then begin
-        let (op_hash, mop) = Queue.pop pipeline.parsing in
-        mop >>= function
-        | Error errs ->
-            record_result pipeline op_hash (Cannot_parse errs);
-            Lwt.return_unit
-        | Ok mop ->
-            let p = Mempool_worker.validate mempool_worker mop in
-            Queue.push (mop, p) pipeline.applying;
-            Lwt.return_unit
-      end
-
       else if head_is_resolved pipeline.downloading then begin
         let (op_hash, p) = Queue.pop pipeline.downloading in
         p >>= function
@@ -175,9 +181,14 @@ module Make (Mempool_worker: Mempool_worker.T)
             record_result pipeline op_hash (Cannot_download errs);
             Lwt.return_unit
         | Ok op ->
-            let p = Mempool_worker.parse mempool_worker op in
-            Queue.push (op_hash, p) pipeline.parsing;
-            Lwt.return_unit
+            match Mempool_worker.parse op with
+            | Error errs ->
+                record_result pipeline op_hash (Cannot_parse errs);
+                Lwt.return_unit
+            | Ok mop ->
+                let p = Mempool_worker.validate mempool_worker mop in
+                Queue.push (mop, p) pipeline.applying;
+                Lwt.return_unit
       end
 
       else if (not (Queue.is_empty pipeline.received)) then begin
@@ -234,7 +245,7 @@ module Make (Mempool_worker: Mempool_worker.T)
   module Event = struct
     type t =
       | Start of input
-      | End_ok of (Request.view * Worker_types.request_status)
+      | End_ok of (Request.view * Worker_types.request_status * output)
       | End_error of (Request.view * Worker_types.request_status * error list)
 
     let level req =
@@ -253,11 +264,12 @@ module Make (Mempool_worker: Mempool_worker.T)
             (fun input -> Start input) ;
           case (Tag 1)
             ~title:"End_ok"
-            (obj2
+            (obj3
                (req "request" Request.encoding)
-               (req "status" Worker_types.request_status_encoding))
-            (function End_ok (view, status) -> Some (view, status) | _ -> None)
-            (fun (view, status) -> End_ok (view, status)) ;
+               (req "status" Worker_types.request_status_encoding)
+               (req "output" (Operation_hash.Map.encoding result_encoding)))
+            (function End_ok (view, status, result) -> Some (view, status, result) | _ -> None)
+            (fun (view, status, result) -> End_ok (view, status, result)) ;
           case (Tag 2)
             ~title:"End_error"
             (obj3
@@ -273,7 +285,7 @@ module Make (Mempool_worker: Mempool_worker.T)
             "@[<v 0>Starting: %a@]"
             pp_input
             input
-      | End_ok (view, _) ->
+      | End_ok (view, _, _) ->
           Format.fprintf ppf
             "@[<v 0>Finished: %a@]"
             Request.pp view
@@ -323,9 +335,11 @@ module Make (Mempool_worker: Mempool_worker.T)
 
     let on_completion
       : type a. self -> a Request.t -> a -> Worker_types.request_status -> unit Lwt.t
-      = fun t r _ st ->
-        Worker.record_event t (Event.End_ok (Request.view r, st)) ;
-        Lwt.return_unit
+      = fun t req output st ->
+        match req with
+        | Request.Batch _ ->
+            Worker.record_event t (Event.End_ok (Request.view req, st, output)) ;
+            Lwt.return_unit
 
   end
 
@@ -337,12 +351,8 @@ module Make (Mempool_worker: Mempool_worker.T)
     Worker.push_request_and_wait t (Request.Batch (mempool_worker, os))
     >>=? fun (_: output) -> return_unit
 
-  let create limits peer_id mempool_worker input =
-    Worker.launch table limits.worker_limits peer_id mempool_worker (module Handlers) >>= fun w ->
-    validate mempool_worker w input >>= fun (_: unit tzresult) ->
-    (* NOTE: We ignore errors here. The validation of the [input] is only for
-     * recycling purposes and is not essential. *)
-    Lwt.return w
+  let create limits peer_id mempool_worker =
+    Worker.launch table limits.worker_limits peer_id mempool_worker (module Handlers)
 
   let shutdown w =
     let recycled = Operation_hash.Set.empty in
diff --git a/src/lib_shell/mempool_peer_worker.mli b/src/lib_shell/mempool_peer_worker.mli
index c16c21e43..014037220 100644
--- a/src/lib_shell/mempool_peer_worker.mli
+++ b/src/lib_shell/mempool_peer_worker.mli
@@ -43,12 +43,11 @@ module type T = sig
    * their validity before gossiping them furhter. *)
   type input = Operation_hash.t list
 
-  (** [create limits peer_id mempool_worker input] creates a peer worker meant
+  (** [create limits peer_id mempool_worker] creates a peer worker meant
    * to be used for validating batches of operations sent by the peer [peer_id].
    * The [mempool_worker] the underlying worker that individual validations of
-   * singular operations are delegated to. The [input[] argument is for recycled
-   * operations that are carried over when the protocol updates. *)
-  val create: limits -> P2p_peer.Id.t -> Mempool_worker.t -> input -> t Lwt.t
+   * singular operations are delegated to. *)
+  val create: limits -> P2p_peer.Id.t -> Mempool_worker.t -> t Lwt.t
 
   (** [shutdown t] closes the peer worker [t]. It returns a list of operation
    * hashes that can be recycled when a new worker is created for the same peer.
diff --git a/src/lib_shell/mempool_worker.ml b/src/lib_shell/mempool_worker.ml
index ca7da1a97..bca7bba98 100644
--- a/src/lib_shell/mempool_worker.ml
+++ b/src/lib_shell/mempool_worker.ml
@@ -45,6 +45,7 @@ module type T = sig
     | Refused of error list
     | Duplicate
     | Not_in_branch
+  val result_encoding : result Data_encoding.t
 
   (** Creates/tear-down a new mempool validator context. *)
   val create : limits -> Distributed_db.chain_db -> t tzresult Lwt.t
diff --git a/src/lib_shell/mempool_worker.mli b/src/lib_shell/mempool_worker.mli
index f5c33e8c9..922c9faee 100644
--- a/src/lib_shell/mempool_worker.mli
+++ b/src/lib_shell/mempool_worker.mli
@@ -46,6 +46,7 @@ module type T = sig
     | Refused of error list
     | Duplicate
     | Not_in_branch
+  val result_encoding : result Data_encoding.t
 
   (** Creates/tear-down a new mempool validator context. *)
   val create : limits -> Distributed_db.chain_db -> t tzresult Lwt.t