diff --git a/lib/vagrant/protobufs/proto/vagrant_plugin_sdk/plugin_pb.rb b/lib/vagrant/protobufs/proto/vagrant_plugin_sdk/plugin_pb.rb
index 6e1a1d710..9a2773ace 100644
--- a/lib/vagrant/protobufs/proto/vagrant_plugin_sdk/plugin_pb.rb
+++ b/lib/vagrant/protobufs/proto/vagrant_plugin_sdk/plugin_pb.rb
@@ -333,21 +333,18 @@ Google::Protobuf::DescriptorPool.generated_pool.build do
       repeated :flags, :message, 4, "hashicorp.vagrant.sdk.Command.Flag"
       repeated :subcommands, :message, 5, "hashicorp.vagrant.sdk.Command.CommandInfo"
     end
-    add_message "hashicorp.vagrant.sdk.Command.CommandInfoReq" do
-      repeated :command_string, :string, 1
-    end
     add_message "hashicorp.vagrant.sdk.Command.CommandInfoResp" do
       optional :command_info, :message, 1, "hashicorp.vagrant.sdk.Command.CommandInfo"
     end
-    add_message "hashicorp.vagrant.sdk.Command.ExecuteReq" do
-      optional :args, :message, 1, "hashicorp.vagrant.sdk.FuncSpec.Args"
-      repeated :command_string, :string, 2
-    end
     add_message "hashicorp.vagrant.sdk.Command.ExecuteResp" do
       optional :exit_code, :int64, 1
     end
-    add_message "hashicorp.vagrant.sdk.Command.SpecReq" do
-      repeated :command_string, :string, 1
+    add_message "hashicorp.vagrant.sdk.Command.ExecuteReq" do
+      optional :spec, :message, 1, "hashicorp.vagrant.sdk.FuncSpec.Args"
+      repeated :command_args, :string, 2
+    end
+    add_message "hashicorp.vagrant.sdk.Command.ExecuteSpecReq" do
+      repeated :command_args, :string, 1
     end
     add_message "hashicorp.vagrant.sdk.Command.Arguments" do
       repeated :flags, :message, 1, "hashicorp.vagrant.sdk.Command.Arguments.Flag"
@@ -619,11 +616,10 @@ module Hashicorp
       Command::Flag = ::Google::Protobuf::DescriptorPool.generated_pool.lookup("hashicorp.vagrant.sdk.Command.Flag").msgclass
       Command::Flag::Type = ::Google::Protobuf::DescriptorPool.generated_pool.lookup("hashicorp.vagrant.sdk.Command.Flag.Type").enummodule
       Command::CommandInfo = ::Google::Protobuf::DescriptorPool.generated_pool.lookup("hashicorp.vagrant.sdk.Command.CommandInfo").msgclass
-      Command::CommandInfoReq = ::Google::Protobuf::DescriptorPool.generated_pool.lookup("hashicorp.vagrant.sdk.Command.CommandInfoReq").msgclass
       Command::CommandInfoResp = ::Google::Protobuf::DescriptorPool.generated_pool.lookup("hashicorp.vagrant.sdk.Command.CommandInfoResp").msgclass
-      Command::ExecuteReq = ::Google::Protobuf::DescriptorPool.generated_pool.lookup("hashicorp.vagrant.sdk.Command.ExecuteReq").msgclass
       Command::ExecuteResp = ::Google::Protobuf::DescriptorPool.generated_pool.lookup("hashicorp.vagrant.sdk.Command.ExecuteResp").msgclass
-      Command::SpecReq = ::Google::Protobuf::DescriptorPool.generated_pool.lookup("hashicorp.vagrant.sdk.Command.SpecReq").msgclass
+      Command::ExecuteReq = ::Google::Protobuf::DescriptorPool.generated_pool.lookup("hashicorp.vagrant.sdk.Command.ExecuteReq").msgclass
+      Command::ExecuteSpecReq = ::Google::Protobuf::DescriptorPool.generated_pool.lookup("hashicorp.vagrant.sdk.Command.ExecuteSpecReq").msgclass
       Command::Arguments = ::Google::Protobuf::DescriptorPool.generated_pool.lookup("hashicorp.vagrant.sdk.Command.Arguments").msgclass
       Command::Arguments::Flag = ::Google::Protobuf::DescriptorPool.generated_pool.lookup("hashicorp.vagrant.sdk.Command.Arguments.Flag").msgclass
       Command::Arguments::Flag::Type = ::Google::Protobuf::DescriptorPool.generated_pool.lookup("hashicorp.vagrant.sdk.Command.Arguments.Flag.Type").enummodule
diff --git a/lib/vagrant/protobufs/proto/vagrant_plugin_sdk/plugin_services_pb.rb b/lib/vagrant/protobufs/proto/vagrant_plugin_sdk/plugin_services_pb.rb
index b59c8c62e..9e353d76a 100644
--- a/lib/vagrant/protobufs/proto/vagrant_plugin_sdk/plugin_services_pb.rb
+++ b/lib/vagrant/protobufs/proto/vagrant_plugin_sdk/plugin_services_pb.rb
@@ -141,10 +141,10 @@ module Hashicorp
           rpc :ConfigStruct, ::Google::Protobuf::Empty, ::Hashicorp::Vagrant::Sdk::Config::StructResp
           rpc :Configure, ::Hashicorp::Vagrant::Sdk::Config::ConfigureRequest, ::Google::Protobuf::Empty
           rpc :Documentation, ::Google::Protobuf::Empty, ::Hashicorp::Vagrant::Sdk::Config::Documentation
-          rpc :ExecuteSpec, ::Hashicorp::Vagrant::Sdk::Command::SpecReq, ::Hashicorp::Vagrant::Sdk::FuncSpec
+          rpc :ExecuteSpec, ::Hashicorp::Vagrant::Sdk::Command::ExecuteSpecReq, ::Hashicorp::Vagrant::Sdk::FuncSpec
           rpc :Execute, ::Hashicorp::Vagrant::Sdk::Command::ExecuteReq, ::Hashicorp::Vagrant::Sdk::Command::ExecuteResp
-          rpc :CommandInfoSpec, ::Hashicorp::Vagrant::Sdk::Command::SpecReq, ::Hashicorp::Vagrant::Sdk::FuncSpec
-          rpc :CommandInfo, ::Hashicorp::Vagrant::Sdk::Command::CommandInfoReq, ::Hashicorp::Vagrant::Sdk::Command::CommandInfoResp
+          rpc :CommandInfoSpec, ::Google::Protobuf::Empty, ::Hashicorp::Vagrant::Sdk::FuncSpec
+          rpc :CommandInfo, ::Hashicorp::Vagrant::Sdk::FuncSpec::Args, ::Hashicorp::Vagrant::Sdk::Command::CommandInfoResp
         end
 
         Stub = Service.rpc_stub_class
diff --git a/plugins/commands/serve/service/command_service.rb b/plugins/commands/serve/service/command_service.rb
index 3abe97a27..2f79b5fb2 100644
--- a/plugins/commands/serve/service/command_service.rb
+++ b/plugins/commands/serve/service/command_service.rb
@@ -18,8 +18,7 @@ module VagrantPlugins
 
         def command_info(req, ctx)
           ServiceInfo.with_info(ctx) do |info|
-            subcommand = req.command_string.to_a[1..]
-            command_info = collect_command_info(info.plugin_name, subcommand)
+            command_info = collect_command_info(info.plugin_name, [])
             LOGGER.info("command info, #{command_info}")
             SDK::Command::CommandInfoResp.new(
               command_info: command_info,
@@ -251,7 +250,7 @@ module VagrantPlugins
               raise "Failed to locate command plugin for: #{plugin_name}"
             end
             cmd_klass = plugin.call
-            cmd_args = req.command_string.to_a[1..] + arguments.args.to_a
+            cmd_args = req.command_args.to_a[1..] + arguments.args.to_a
             cmd = cmd_klass.new(cmd_args, env)
             result = cmd.execute