Add env vars to servers through stdio client

client/stdio.go

@@ -36,10 +36,13 @@ type StdioMCPClient struct {
 // Returns an error if the subprocess cannot be started or the pipes cannot be created.
 func NewStdioMCPClient(
 	command string,
+	env []string,
 	args ...string,
 ) (*StdioMCPClient, error) {
 	cmd := exec.Command(command, args...)
 
+	cmd.Env = env
+
 	stdin, err := cmd.StdinPipe()
 	if err != nil {
 		return nil, fmt.Errorf("failed to create stdin pipe: %w", err)

client/stdio_test.go

@@ -34,7 +34,7 @@ func TestStdioMCPClient(t *testing.T) {
 	}
 	defer os.Remove(mockServerPath)
 
-	client, err := NewStdioMCPClient(mockServerPath)
+	client, err := NewStdioMCPClient(mockServerPath, []string{})
 	if err != nil {
 		t.Fatalf("Failed to create client: %v", err)
 	}

examples/filesystem_stdio_client/main.go

@@ -16,6 +16,7 @@ func main() {
 	// Using npx to run the filesystem server with /tmp as the only allowed directory
 	c, err := client.NewStdioMCPClient(
 		"go",
+		[]string{}, // Empty ENV
 		"run",
 		"github.com/mark3labs/mcp-filesystem-server@latest",
 		"/tmp",