diff --git a/tools_read.go b/tools_read.go
index 657dc2b..8460ba7 100644
--- a/tools_read.go
+++ b/tools_read.go
@@ -108,10 +108,13 @@ func (d *deps) handlePagePerceive(_ context.Context, _ mcp.CallToolRequest, a pa
 		}
 	}
 
+	// `fn run` pasa los argumentos POSICIONALMENTE a la función del pipeline
+	// (no como flags argparse): el orden debe coincidir con la firma
+	// cdp_perceive_outline(debug_port, tab_id, max_chars).
 	cmd := exec.Command(filepath.Join(root, "fn"), "run", "cdp_perceive_outline",
-		"--debug-port", fmt.Sprint(port),
-		"--tab-id", tabID,
-		"--max-chars", fmt.Sprint(maxChars),
+		fmt.Sprint(port),
+		tabID,
+		fmt.Sprint(maxChars),
 	)
 	cmd.Dir = root
 	var stdout, stderr strings.Builder