diff --git a/src/server/stream_family.cc b/src/server/stream_family.cc
index 444701393982..07ce58444736 100644
--- a/src/server/stream_family.cc
+++ b/src/server/stream_family.cc
@@ -1797,19 +1797,18 @@ OpResult<PendingResult> OpPending(const OpArgs& op_args, string_view key, const
   return result;
 }
 
-void CreateGroup(CmdArgList args, string_view key, ConnectionContext* cntx) {
-  if (args.size() < 2)
-    return cntx->SendError(UnknownSubCmd("CREATE", "XGROUP"));
+void CreateGroup(facade::CmdArgParser* parser, ConnectionContext* cntx) {
+  auto key = parser->Next();
 
   CreateOpts opts;
-  opts.gname = ArgS(args, 0);
-  opts.id = ArgS(args, 1);
-  if (args.size() >= 3) {
-    ToUpper(&args[2]);
-    if (ArgS(args, 2) == "MKSTREAM")
-      opts.flags |= kCreateOptMkstream;
+  std::tie(opts.gname, opts.id) = parser->Next<string_view, string_view>();
+  if (parser->Check("MKSTREAM")) {
+    opts.flags |= kCreateOptMkstream;
   }
 
+  if (auto err = parser->Error(); err)
+    return cntx->SendError(err->MakeReply());
+
   auto cb = [&](Transaction* t, EngineShard* shard) {
     return OpCreate(t->GetOpArgs(shard), key, opts);
   };
@@ -1823,7 +1822,15 @@ void CreateGroup(CmdArgList args, string_view key, ConnectionContext* cntx) {
   }
 }
 
-void DestroyGroup(string_view key, string_view gname, ConnectionContext* cntx) {
+void DestroyGroup(facade::CmdArgParser* parser, ConnectionContext* cntx) {
+  auto [key, gname] = parser->Next<string_view, string_view>();
+
+  if (auto err = parser->Error(); err)
+    return cntx->SendError(err->MakeReply());
+
+  if (parser->HasNext())
+    return cntx->SendError(UnknownSubCmd("DESTROY", "XGROUP"));
+
   auto cb = [&](Transaction* t, EngineShard* shard) {
     return OpDestroyGroup(t->GetOpArgs(shard), key, gname);
   };
@@ -1841,8 +1848,15 @@ void DestroyGroup(string_view key, string_view gname, ConnectionContext* cntx) {
   }
 }
 
-void CreateConsumer(string_view key, string_view gname, string_view consumer,
-                    ConnectionContext* cntx) {
+void CreateConsumer(facade::CmdArgParser* parser, ConnectionContext* cntx) {
+  auto [key, gname, consumer] = parser->Next<string_view, string_view, string_view>();
+
+  if (auto err = parser->Error(); err)
+    return cntx->SendError(err->MakeReply());
+
+  if (parser->HasNext())
+    return cntx->SendError(UnknownSubCmd("CREATECONSUMER", "XGROUP"));
+
   auto cb = [&](Transaction* t, EngineShard* shard) {
     return OpCreateConsumer(t->GetOpArgs(shard), key, gname, consumer);
   };
@@ -1862,8 +1876,15 @@ void CreateConsumer(string_view key, string_view gname, string_view consumer,
   }
 }
 
-void DelConsumer(string_view key, string_view gname, string_view consumer,
-                 ConnectionContext* cntx) {
+void DelConsumer(facade::CmdArgParser* parser, ConnectionContext* cntx) {
+  auto [key, gname, consumer] = parser->Next<string_view, string_view, string_view>();
+
+  if (auto err = parser->Error(); err)
+    return cntx->SendError(err->MakeReply());
+
+  if (parser->HasNext())
+    return cntx->SendError(UnknownSubCmd("DELCONSUMER", "XGROUP"));
+
   auto cb = [&](Transaction* t, EngineShard* shard) {
     return OpDelConsumer(t->GetOpArgs(shard), key, gname, consumer);
   };
@@ -1882,18 +1903,21 @@ void DelConsumer(string_view key, string_view gname, string_view consumer,
   }
 }
 
-void SetId(string_view key, string_view gname, CmdArgList args, ConnectionContext* cntx) {
-  facade::CmdArgParser parser{args};
+void SetId(facade::CmdArgParser* parser, ConnectionContext* cntx) {
+  auto [key, gname, id] = parser->Next<string_view, string_view, string_view>();
 
-  string_view id = parser.Next();
-  while (parser.HasNext()) {
-    if (parser.Check("ENTRIESREAD")) {
+  while (parser->HasNext()) {
+    if (parser->Check("ENTRIESREAD")) {
       // TODO: to support ENTRIESREAD.
       return cntx->SendError(kSyntaxErr);
     } else {
       return cntx->SendError(kSyntaxErr);
     }
   }
+
+  if (auto err = parser->Error(); err)
+    return cntx->SendError(err->MakeReply());
+
   auto cb = [&](Transaction* t, EngineShard* shard) {
     return OpSetId(t->GetOpArgs(shard), key, gname, id);
   };
@@ -1910,20 +1934,23 @@ void SetId(string_view key, string_view gname, CmdArgList args, ConnectionContex
 }
 
 void XGroupHelp(CmdArgList args, ConnectionContext* cntx) {
-  string_view help_arr[] = {
-      "CREATE <key> <groupname> <id|$> [option]",
-      "    Create a new consumer group. Options are:",
-      "    * MKSTREAM",
-      "      Create the empty stream if it does not exist.",
-      "CREATECONSUMER <key> <groupname> <consumer>",
-      "    Create a new consumer in the specified group.",
-      "DELCONSUMER <key> <groupname> <consumer>",
-      "    Remove the specified consumer.",
-      "DESTROY <key> <groupname>",
-      "    Remove the specified group.",
-      "SETID <key> <groupname> <id|$>",
-      "    Set the current group ID.",
-  };
+  string_view help_arr[] = {"XGROUP <subcommand> [<arg> [value] [opt] ...]. Subcommands are:",
+                            "CREATE <key> <groupname> <id|$> [option]",
+                            "    Create a new consumer group. Options are:",
+                            "    * MKSTREAM",
+                            "      Create the empty stream if it does not exist.",
+                            "    * ENTRIESREAD entries_read",
+                            "      Set the group's entries_read counter (internal use).",
+                            "CREATECONSUMER <key> <groupname> <consumer>",
+                            "    Create a new consumer in the specified group.",
+                            "DELCONSUMER <key> <groupname> <consumer>",
+                            "    Remove the specified consumer.",
+                            "DESTROY <key> <groupname>",
+                            "    Remove the specified group.",
+                            "SETID <key> <groupname> <id|$> [ENTRIESREAD entries_read]",
+                            "    Set the current group ID and entries_read counter.",
+                            "HELP",
+                            "    Print this help."};
   auto* rb = static_cast<RedisReplyBuilder*>(cntx->reply_builder());
   return rb->SendSimpleStrArr(help_arr);
 }
@@ -2316,63 +2343,21 @@ void StreamFamily::XDel(CmdArgList args, ConnectionContext* cntx) {
   cntx->SendError(result.status());
 }
 
+void HelpSubCmd(facade::CmdArgParser* parser, ConnectionContext* cntx) {
+  XGroupHelp(parser->Tail(), cntx);
+}
+
 void StreamFamily::XGroup(CmdArgList args, ConnectionContext* cntx) {
   facade::CmdArgParser parser{args};
 
-  string_view sub_cmd = parser.ToUpper().Next();
-  if (sub_cmd == "HELP") {
-    string_view help[] = {"XGROUP <subcommand> [<arg> [value] [opt] ...]. Subcommands are:",
-                          "CREATE <key> <groupname> <id|$> [option]",
-                          "    Create a new consumer group. Options are:",
-                          "    * MKSTREAM",
-                          "      Create the empty stream if it does not exist.",
-                          "    * ENTRIESREAD entries_read",
-                          "      Set the group's entries_read counter (internal use).",
-                          "CREATECONSUMER <key> <groupname> <consumer>",
-                          "    Create a new consumer in the specified group.",
-                          "DELCONSUMER <key> <groupname> <consumer>",
-                          "    Remove the specified consumer.",
-                          "DESTROY <key> <groupname>",
-                          "    Remove the specified group.",
-                          "SETID <key> <groupname> <id|$> [ENTRIESREAD entries_read]",
-                          "    Set the current group ID and entries_read counter.",
-                          "HELP",
-                          "    Print this help."};
-    auto* rb = static_cast<RedisReplyBuilder*>(cntx->reply_builder());
-    return rb->SendStringArr(help);
-  }
-
-  if (!parser.HasAtLeast(2))
-    return cntx->SendError(kSyntaxErr, kScriptErrType);
-
-  string_view key = parser.Next();
-
-  if (sub_cmd == "CREATE") {
-    args.remove_prefix(2);
-    return CreateGroup(std::move(args), key, cntx);
-  }
+  const auto* sub_cmd_func = parser.MapNext("HELP", &HelpSubCmd, "CREATE", &CreateGroup, "DESTROY",
+                                            &DestroyGroup, "CREATECONSUMER", &CreateConsumer,
+                                            "DELCONSUMER", &DelConsumer, "SETID", &SetId);
 
-  string_view gname = parser.Next();
-  if (sub_cmd == "DESTROY" && args.size() == 3) {
-    return DestroyGroup(key, gname, cntx);
-  }
-
-  if (sub_cmd == "CREATECONSUMER" && args.size() == 4) {
-    string_view cname = parser.Next();
-    return CreateConsumer(key, gname, cname, cntx);
-  }
-
-  if (sub_cmd == "DELCONSUMER" && args.size() == 4) {
-    string_view cname = parser.Next();
-    return DelConsumer(key, gname, cname, cntx);
-  }
-
-  if (sub_cmd == "SETID" && args.size() >= 4) {
-    args.remove_prefix(3);
-    return SetId(key, gname, std::move(args), cntx);
-  }
+  if (auto err = parser.Error(); err)
+    return cntx->SendError(err->MakeReply());
 
-  return cntx->SendError(UnknownSubCmd(sub_cmd, "XGROUP"));
+  sub_cmd_func(&parser, cntx);
 }
 
 void StreamFamily::XInfo(CmdArgList args, ConnectionContext* cntx) {