diff --git a/src/cmdforge/cli/registry_commands.py b/src/cmdforge/cli/registry_commands.py
index de3071d..f2805f6 100644
--- a/src/cmdforge/cli/registry_commands.py
+++ b/src/cmdforge/cli/registry_commands.py
@@ -414,13 +414,44 @@ def _cmd_registry_publish(args):
         return 1
 
     if args.dry_run:
-        print("Dry run - validating only")
+        print("Dry run — validating locally and via registry preflight")
         print()
-        print(f"Would publish:")
+
+        # Local validation
         print(f"  Name: {name}")
         print(f"  Version: {version}")
         print(f"  Config: {len(config_yaml)} bytes")
         print(f"  README: {len(readme)} bytes")
+        print()
+
+        # Attempt registry preflight if token is configured
+        config = load_config()
+        if config.registry.token:
+            try:
+                client = get_client()
+                result = client.publish_tool(
+                    config_yaml, readme=readme, defaults=defaults,
+                    dry_run=True,
+                )
+                errors = result.get("errors") or []
+                warnings = result.get("warnings") or []
+                if errors:
+                    print(f"Preflight errors ({len(errors)}):")
+                    for err in errors:
+                        print(f"  ERROR: {err}")
+                if warnings:
+                    print(f"Preflight warnings ({len(warnings)}):")
+                    for warn in warnings:
+                        print(f"  WARN: {warn}")
+                if not errors and not warnings:
+                    print("Registry preflight passed.")
+                return 0 if not errors else 1
+            except Exception as e:
+                print(f"Registry preflight unavailable: {e}")
+                print("Proceeding with local validation only.")
+        else:
+            print("No registry token configured — local validation only.")
+            print("Configure a token to get registry-side preflight checks.")
         return 0
 
     # Check for token
diff --git a/src/cmdforge/gui/pages/tool_builder_page.py b/src/cmdforge/gui/pages/tool_builder_page.py
index e12923a..a4bd1c6 100644
--- a/src/cmdforge/gui/pages/tool_builder_page.py
+++ b/src/cmdforge/gui/pages/tool_builder_page.py
@@ -13,7 +13,7 @@ from PySide6.QtCore import Qt
 
 from ...tool import (
     Tool, ToolArgument, PromptStep, CodeStep, ToolStep,
-    load_tool, save_tool, validate_tool_name, get_all_categories,
+    load_tool, save_tool, tool_exists, validate_tool_name, get_all_categories,
     ensure_settings
 )
 from ..widgets.icons import get_prompt_icon, get_code_icon, get_tool_icon
@@ -1075,6 +1075,41 @@ class ToolBuilderPage(QWidget):
             QMessageBox.warning(self, "Validation", error)
             return
 
+        # Block silent overwrite when creating a new tool
+        if (not self.editing or name != self.original_name) and tool_exists(name):
+            existing = load_tool(name)
+            existing_desc = f" ({existing.description})" if existing and existing.description else ""
+            msg = QMessageBox(self)
+            msg.setIcon(QMessageBox.Warning)
+            msg.setWindowTitle("Tool Already Exists")
+            msg.setText(f"'{name}' already exists.{existing_desc}")
+            msg.setInformativeText("What would you like to do?")
+            btn_open = msg.addButton("Open Existing", QMessageBox.ActionRole)
+            btn_copy = msg.addButton("Create Copy", QMessageBox.ActionRole)
+            btn_rename = msg.addButton("Choose Another Name", QMessageBox.ActionRole)
+            msg.setStandardButtons(QMessageBox.Cancel)
+            msg.setDefaultButton(btn_rename)
+            msg.exec()
+
+            clicked = msg.clickedButton()
+            if clicked is btn_open:
+                self.main_window.open_tool_builder(name)
+                self.main_window.close_tool_builder()
+                return
+            elif clicked is btn_copy:
+                suffix = 2
+                while tool_exists(f"{name}-{suffix}"):
+                    suffix += 1
+                copy_name = f"{name}-{suffix}"
+                self.name_input.setText(copy_name)
+                self.name_input.setFocus()
+                return
+            elif clicked is btn_rename:
+                self.name_input.setFocus()
+                return
+            else:
+                return
+
         description = self.desc_input.text().strip()
         category = self.category_combo.currentText()
         output = self.output_input.toPlainText().strip() or "{response}"