refactor: updated the handler traits and fixed error handling for mcp

error messages

Author: hashemix

crates/rust-mcp-sdk/src/mcp_handlers/mcp_client_handler.rs

@@ -148,7 +148,7 @@ pub trait ClientHandler: Send + Sync + 'static {
     //********************//
     async fn handle_error(
         &self,
-        error: RpcError,
+        error: &RpcError,
         runtime: &dyn McpClient,
     ) -> std::result::Result<(), RpcError> {
         Ok(())

crates/rust-mcp-sdk/src/mcp_handlers/mcp_client_handler_core.rs

@@ -38,7 +38,7 @@ pub trait ClientHandlerCore: Send + Sync + 'static {
     /// - `error` – The error data received from the MCP server.
     async fn handle_error(
         &self,
-        error: RpcError,
+        error: &RpcError,
         runtime: &dyn McpClient,
     ) -> std::result::Result<(), RpcError>;
 

crates/rust-mcp-sdk/src/mcp_handlers/mcp_server_handler.rs

@@ -319,7 +319,7 @@ pub trait ServerHandler: Send + Sync + 'static {
     /// Customize this function in your specific handler to implement behavior tailored to your MCP server's capabilities and requirements.
     async fn handle_error(
         &self,
-        error: RpcError,
+        error: &RpcError,
         runtime: &dyn McpServer,
     ) -> std::result::Result<(), RpcError> {
         Ok(())

crates/rust-mcp-sdk/src/mcp_handlers/mcp_server_handler_core.rs

@@ -45,7 +45,7 @@ pub trait ServerHandlerCore: Send + Sync + 'static {
     /// - `error` – The error data received from the MCP client.
     async fn handle_error(
         &self,
-        error: RpcError,
+        error: &RpcError,
         runtime: &dyn McpServer,
     ) -> std::result::Result<(), RpcError>;
     async fn on_server_started(&self, runtime: &dyn McpServer) {

crates/rust-mcp-sdk/src/mcp_runtimes/client_runtime.rs

@@ -130,7 +130,19 @@ impl ClientRuntime {
                 None
             }
             ServerMessage::Error(jsonrpc_error) => {
-                self.handler.handle_error(jsonrpc_error.error, self).await?;
+                self.handler
+                    .handle_error(&jsonrpc_error.error, self)
+                    .await?;
+                if let Some(tx_response) = transport.pending_request_tx(&jsonrpc_error.id).await {
+                    tx_response
+                        .send(ServerMessage::Error(jsonrpc_error))
+                        .map_err(|e| RpcError::internal_error().with_message(e.to_string()))?;
+                } else {
+                    tracing::warn!(
+                        "Received an error response with no corresponding request: {:?}",
+                        &jsonrpc_error.id
+                    );
+                }
                 None
             }
             ServerMessage::Response(response) => {
@@ -140,7 +152,7 @@ impl ClientRuntime {
                         .map_err(|e| RpcError::internal_error().with_message(e.to_string()))?;
                 } else {
                     tracing::warn!(
-                        "Received response or error without a matching request: {:?}",
+                        "Received a response with no corresponding request: {:?}",
                         &response.id
                     );
                 }

crates/rust-mcp-sdk/src/mcp_runtimes/client_runtime/mcp_client_runtime.rs

@@ -113,7 +113,7 @@ impl McpClientHandler for ClientInternalHandler<Box<dyn ClientHandler>> {
     /// Handles errors received from the server by passing the request to self.handler
     async fn handle_error(
         &self,
-        jsonrpc_error: RpcError,
+        jsonrpc_error: &RpcError,
         runtime: &dyn McpClient,
     ) -> SdkResult<()> {
         self.handler.handle_error(jsonrpc_error, runtime).await?;

crates/rust-mcp-sdk/src/mcp_runtimes/client_runtime/mcp_client_runtime_core.rs

@@ -83,7 +83,7 @@ impl McpClientHandler for ClientCoreInternalHandler<Box<dyn ClientHandlerCore>>
 
     async fn handle_error(
         &self,
-        jsonrpc_error: RpcError,
+        jsonrpc_error: &RpcError,
         runtime: &dyn McpClient,
     ) -> SdkResult<()> {
         self.handler.handle_error(jsonrpc_error, runtime).await?;

crates/rust-mcp-sdk/src/mcp_runtimes/server_runtime.rs

@@ -261,7 +261,19 @@ impl ServerRuntime {
                 None
             }
             ClientMessage::Error(jsonrpc_error) => {
-                self.handler.handle_error(jsonrpc_error.error, self).await?;
+                self.handler
+                    .handle_error(&jsonrpc_error.error, self)
+                    .await?;
+                if let Some(tx_response) = transport.pending_request_tx(&jsonrpc_error.id).await {
+                    tx_response
+                        .send(ClientMessage::Error(jsonrpc_error))
+                        .map_err(|e| RpcError::internal_error().with_message(e.to_string()))?;
+                } else {
+                    tracing::warn!(
+                        "Received an error response with no corresponding request {:?}",
+                        &jsonrpc_error.id
+                    );
+                }
                 None
             }
             // The response is the result of a request, it is processed at the transport level.
@@ -272,7 +284,7 @@ impl ServerRuntime {
                         .map_err(|e| RpcError::internal_error().with_message(e.to_string()))?;
                 } else {
                     tracing::warn!(
-                        "Received response or error without a matching request: {:?}",
+                        "Received a response with no corresponding request: {:?}",
                         &response.id
                     );
                 }

crates/rust-mcp-sdk/src/mcp_runtimes/server_runtime/mcp_server_runtime.rs

@@ -177,7 +177,7 @@ impl McpServerHandler for ServerRuntimeInternalHandler<Box<dyn ServerHandler>> {
 
     async fn handle_error(
         &self,
-        jsonrpc_error: RpcError,
+        jsonrpc_error: &RpcError,
         runtime: &dyn McpServer,
     ) -> SdkResult<()> {
         self.handler.handle_error(jsonrpc_error, runtime).await?;

crates/rust-mcp-sdk/src/mcp_runtimes/server_runtime/mcp_server_runtime_core.rs

@@ -87,7 +87,7 @@ impl McpServerHandler for RuntimeCoreInternalHandler<Box<dyn ServerHandlerCore>>
     }
     async fn handle_error(
         &self,
-        jsonrpc_error: RpcError,
+        jsonrpc_error: &RpcError,
         runtime: &dyn McpServer,
     ) -> SdkResult<()> {
         self.handler.handle_error(jsonrpc_error, runtime).await?;