diff --git a/rpc-toolkit/src/cli.rs b/rpc-toolkit/src/cli.rs
index 11f9a9c..9e0c993 100644
--- a/rpc-toolkit/src/cli.rs
+++ b/rpc-toolkit/src/cli.rs
@@ -15,7 +15,7 @@ use yajrc::{Id, RpcError};
 
 use crate::util::{internal_error, parse_error, PhantomData};
 use crate::{
-    AnyHandler, CliBindingsAny, DynHandler, HandleAny, HandleAnyArgs, Handler, HandlerArgs,
+    AnyHandler, CliBindingsAny, DynHandler, Empty, HandleAny, HandleAnyArgs, Handler, HandlerArgs,
     HandlerArgsFor, HandlerTypes, IntoContext, Name, ParentHandler, PrintCliResult,
 };
 
@@ -84,11 +84,12 @@ impl<Context: crate::Context + Clone, Config: CommandFactory + FromArgMatches>
     }
 }
 
-pub trait CallRemote<RemoteContext>: crate::Context {
+pub trait CallRemote<RemoteContext, Extra = Empty>: crate::Context {
     fn call_remote(
         &self,
         method: &str,
         params: Value,
+        extra: Extra,
     ) -> impl Future<Output = Result<Value, RpcError>> + Send;
 }
 
@@ -171,7 +172,7 @@ pub async fn call_remote_socket(
         .result
 }
 
-pub struct CallRemoteHandler<Context, RemoteHandler> {
+struct CallRemoteHandler<Context, RemoteHandler> {
     _phantom: PhantomData<Context>,
     handler: RemoteHandler,
 }
@@ -232,7 +233,11 @@ where
             .collect::<Vec<_>>();
         match handle_args
             .context
-            .call_remote(&full_method.join("."), handle_args.raw_params.clone())
+            .call_remote(
+                &full_method.join("."),
+                handle_args.raw_params.clone(),
+                Empty {},
+            )
             .await
         {
             Ok(a) => imbl_value::from_value(a)
diff --git a/rpc-toolkit/src/handler/adapters.rs b/rpc-toolkit/src/handler/adapters.rs
index 7d9ad75..c5cdf8d 100644
--- a/rpc-toolkit/src/handler/adapters.rs
+++ b/rpc-toolkit/src/handler/adapters.rs
@@ -10,11 +10,11 @@ use serde::de::DeserializeOwned;
 use serde::Serialize;
 use yajrc::RpcError;
 
-use crate::util::{internal_error, Flat, PhantomData};
+use crate::util::{internal_error, invalid_params, without, Flat, PhantomData};
 use crate::{
     iter_from_ctx_and_handler, AnyContext, AnyHandler, CallRemote, CliBindings, DynHandler,
-    EitherContext, Handler, HandlerArgs, HandlerArgsFor, HandlerTypes, IntoContext, IntoHandlers,
-    OrEmpty, PrintCliResult,
+    EitherContext, Empty, Handler, HandlerArgs, HandlerArgsFor, HandlerTypes, IntoContext,
+    IntoHandlers, OrEmpty, PrintCliResult,
 };
 
 pub trait HandlerExt: Handler + Sized {
@@ -40,7 +40,7 @@ pub trait HandlerExt: Handler + Sized {
     ) -> InheritanceHandler<Params, InheritedParams, Self, F>
     where
         F: Fn(Params, InheritedParams) -> Self::InheritedParams;
-    fn with_call_remote<Context>(self) -> RemoteCaller<Context, Self>;
+    fn with_call_remote<Context, Extra>(self) -> RemoteCaller<Context, Self, Extra>;
 }
 
 impl<T: Handler + Sized> HandlerExt for T {
@@ -90,7 +90,7 @@ impl<T: Handler + Sized> HandlerExt for T {
             inherit: f,
         }
     }
-    fn with_call_remote<Context>(self) -> RemoteCaller<Context, Self> {
+    fn with_call_remote<Context, Extra>(self) -> RemoteCaller<Context, Self, Extra> {
         RemoteCaller {
             _phantom: PhantomData::new(),
             handler: self,
@@ -452,11 +452,11 @@ where
     }
 }
 
-pub struct RemoteCaller<Context, H> {
-    _phantom: PhantomData<Context>,
+pub struct RemoteCaller<Context, H, Extra = Empty> {
+    _phantom: PhantomData<(Context, Extra)>,
     handler: H,
 }
-impl<Context, H: Clone> Clone for RemoteCaller<Context, H> {
+impl<Context, H: Clone, Extra> Clone for RemoteCaller<Context, H, Extra> {
     fn clone(&self) -> Self {
         Self {
             _phantom: PhantomData::new(),
@@ -464,29 +464,31 @@ impl<Context, H: Clone> Clone for RemoteCaller<Context, H> {
         }
     }
 }
-impl<Context, H: Debug> Debug for RemoteCaller<Context, H> {
+impl<Context, H: Debug, Extra> Debug for RemoteCaller<Context, H, Extra> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         f.debug_tuple("RemoteCaller").field(&self.handler).finish()
     }
 }
-impl<Context, H> HandlerTypes for RemoteCaller<Context, H>
+impl<Context, H, Extra> HandlerTypes for RemoteCaller<Context, H, Extra>
 where
     H: HandlerTypes,
+    Extra: Send + Sync + 'static,
 {
-    type Params = H::Params;
+    type Params = Flat<H::Params, Extra>;
     type InheritedParams = H::InheritedParams;
     type Ok = H::Ok;
     type Err = H::Err;
 }
 
-impl<Context, H> Handler for RemoteCaller<Context, H>
+impl<Context, H, Extra> Handler for RemoteCaller<Context, H, Extra>
 where
-    Context: CallRemote<H::Context>,
+    Context: CallRemote<H::Context, Extra>,
     H: Handler,
     H::Params: Serialize,
     H::InheritedParams: Serialize,
     H::Ok: DeserializeOwned,
     H::Err: From<RpcError>,
+    Extra: Serialize + Send + Sync + 'static,
 {
     type Context = EitherContext<Context, H::Context>;
     async fn handle_async(
@@ -495,7 +497,7 @@ where
             context,
             parent_method,
             method,
-            params,
+            params: Flat(params, extra),
             inherited_params,
             raw_params,
         }: HandlerArgsFor<Self::Context, Self>,
@@ -504,7 +506,11 @@ where
             EitherContext::C1(context) => {
                 let full_method = parent_method.into_iter().chain(method).collect::<Vec<_>>();
                 match context
-                    .call_remote(&full_method.join("."), raw_params.clone())
+                    .call_remote(
+                        &full_method.join("."),
+                        without(raw_params, &extra).map_err(invalid_params)?,
+                        extra,
+                    )
                     .await
                 {
                     Ok(a) => imbl_value::from_value(a)
@@ -553,7 +559,7 @@ where
             context,
             parent_method,
             method,
-            params,
+            params: Flat(params, _),
             inherited_params,
             raw_params,
         }: HandlerArgsFor<Self::Context, Self>,
diff --git a/rpc-toolkit/src/util.rs b/rpc-toolkit/src/util.rs
index b457e58..c7b71b2 100644
--- a/rpc-toolkit/src/util.rs
+++ b/rpc-toolkit/src/util.rs
@@ -10,10 +10,21 @@ use serde::{Deserialize, Serialize};
 use yajrc::RpcError;
 
 pub fn extract<T: DeserializeOwned>(value: &Value) -> Result<T, RpcError> {
-    imbl_value::from_value(value.clone()).map_err(|e| RpcError {
-        data: Some(e.to_string().into()),
-        ..yajrc::INVALID_PARAMS_ERROR
-    })
+    imbl_value::from_value(value.clone()).map_err(invalid_params)
+}
+
+pub fn without<T: Serialize>(value: Value, remove: &T) -> Result<Value, imbl_value::Error> {
+    let to_remove = imbl_value::to_value(remove)?;
+    let (Value::Object(mut value), Value::Object(to_remove)) = (value, to_remove) else {
+        return Err(imbl_value::Error {
+            kind: imbl_value::ErrorKind::Serialization,
+            source: serde_json::Error::custom("params must be object"),
+        });
+    };
+    for k in to_remove.keys() {
+        value.remove(k);
+    }
+    Ok(Value::Object(value))
 }
 
 pub fn combine(v1: Value, v2: Value) -> Result<Value, imbl_value::Error> {
@@ -103,6 +114,49 @@ where
         .serialize(serializer)
     }
 }
+impl<A, B> clap::CommandFactory for Flat<A, B>
+where
+    A: clap::CommandFactory,
+    B: clap::Args,
+{
+    fn command() -> clap::Command {
+        B::augment_args(A::command())
+    }
+    fn command_for_update() -> clap::Command {
+        B::augment_args_for_update(A::command_for_update())
+    }
+}
+impl<A, B> clap::FromArgMatches for Flat<A, B>
+where
+    A: clap::FromArgMatches,
+    B: clap::FromArgMatches,
+{
+    fn from_arg_matches(matches: &clap::ArgMatches) -> Result<Self, clap::Error> {
+        Ok(Self(
+            A::from_arg_matches(matches)?,
+            B::from_arg_matches(matches)?,
+        ))
+    }
+    fn from_arg_matches_mut(matches: &mut clap::ArgMatches) -> Result<Self, clap::Error> {
+        Ok(Self(
+            A::from_arg_matches_mut(matches)?,
+            B::from_arg_matches_mut(matches)?,
+        ))
+    }
+    fn update_from_arg_matches(&mut self, matches: &clap::ArgMatches) -> Result<(), clap::Error> {
+        self.0.update_from_arg_matches(matches)?;
+        self.1.update_from_arg_matches(matches)?;
+        Ok(())
+    }
+    fn update_from_arg_matches_mut(
+        &mut self,
+        matches: &mut clap::ArgMatches,
+    ) -> Result<(), clap::Error> {
+        self.0.update_from_arg_matches_mut(matches)?;
+        self.1.update_from_arg_matches_mut(matches)?;
+        Ok(())
+    }
+}
 
 pub fn poll_select_all<'a, T>(
     futs: &mut Vec<BoxFuture<'a, T>>,
diff --git a/rpc-toolkit/tests/handler.rs b/rpc-toolkit/tests/handler.rs
index ea599c5..5eb3929 100644
--- a/rpc-toolkit/tests/handler.rs
+++ b/rpc-toolkit/tests/handler.rs
@@ -62,7 +62,7 @@ impl Context for CliContext {
 }
 
 impl CallRemote<ServerContext> for CliContext {
-    async fn call_remote(&self, method: &str, params: Value) -> Result<Value, RpcError> {
+    async fn call_remote(&self, method: &str, params: Value, _: Empty) -> Result<Value, RpcError> {
         call_remote_socket(
             tokio::net::UnixStream::connect(&self.0.host).await.unwrap(),
             method,
@@ -129,7 +129,7 @@ fn make_api() -> ParentHandler {
                     ))
                 },
             )
-            .with_call_remote::<CliContext>(),
+            .with_call_remote::<CliContext, Empty>(),
         )
         .subcommand(
             "hello",