From 7f34e8a12cff7015327375dc56be030014a77f35 Mon Sep 17 00:00:00 2001
From: Luxferre <lux@ferre>
Date: Sun, 22 Mar 2026 13:32:41 +0200
Subject: [PATCH] fixed stdio mcp tool usage

---
 mcp.go | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/mcp.go b/mcp.go
index 4eb9986..fc8671e 100644
--- a/mcp.go
+++ b/mcp.go
@@ -4,6 +4,7 @@ import (
   "context"
   "encoding/json"
   "fmt"
+  "io"
   "os"
   "os/exec"
   "strings"
@@ -165,13 +166,11 @@ var defaultMCPFactory MCPClientFactory = func(toolset string) (MCPClientInterfac
       env = os.Environ()
     }
 
-    // Use WithCommandFunc and redirect Stderr directly to os.Stderr
-    // This provides the most reliable way to see subprocess errors
+    // Use WithCommandFunc to configure the command environment
     c, err = client.NewStdioMCPClientWithOptions(command, env, args,
       transport.WithCommandFunc(func(ctx context.Context, command string, env []string, args []string) (*exec.Cmd, error) {
         cmd := exec.CommandContext(ctx, command, args...)
         cmd.Env = env
-        cmd.Stderr = os.Stderr
         return cmd, nil
       }),
     )
@@ -209,6 +208,13 @@ var defaultMCPFactory MCPClientFactory = func(toolset string) (MCPClientInterfac
     return nil, err
   }
 
+  // Redirect stderr from the stdio transport to os.Stderr
+  if cfg.Transport == "stdio" {
+    if stderr, ok := client.GetStderr(c); ok {
+      go io.Copy(os.Stderr, stderr)
+    }
+  }
+
   // Initialize the client session
   initReq := mcp.InitializeRequest{}
   initReq.Params.ProtocolVersion = mcp.LATEST_PROTOCOL_VERSION