Document AI-assisted code generation in README

Co-Authored-By: Claude Opus 4.5 <[email protected]>

README.md

@@ -426,9 +426,12 @@ The graphical interface provides a modern desktop experience:
 ### Tool Builder
 - Visual form for creating and editing tools
 - Add arguments with flags and default values
-- Add prompt steps (AI calls) or code steps (Python)
-- Preview the generated YAML configuration
-- Test tools before saving
+- Add prompt steps (AI calls) with profile selection
+- Add code steps with **AI-assisted code generation**:
+  - Split view: code editor + AI assist panel
+  - Describe what you want and generate Python code
+  - Shows available variables from arguments and previous steps
+  - Automatic markdown fence stripping from AI responses
 
 ### Registry Browser
 - **Browse all** tools on page load (no search required)