docs: note CLI-backend capability transport limitation for show_widget

steipete · steipete · commit 2ab460cee0f7 · 2026-07-09T01:55:39.000-07:00
Related: #101790
diff --git a/docs/tools/show-widget.md b/docs/tools/show-widget.md
@@ -11,6 +11,8 @@ read_when:
 
 The tool is available only when the originating Gateway client declares the `inline-widgets` capability. The Control UI declares this capability automatically. Channel runs such as Telegram and WhatsApp do not receive `show_widget`.
 
+Capability transport currently covers the embedded runner and the Codex app-server backend. CLI-backed model backends do not yet carry client capabilities, so capability-gated tools stay unavailable (fail closed) on those backends.
+
 ## Use the tool
 
 The agent supplies two required strings:
