diff --git a/codex-rs/ext/image-generation/imagegen_description.md b/codex-rs/ext/image-generation/imagegen_description.md
index 2d9b96187a..368aa10ea8 100644
--- a/codex-rs/ext/image-generation/imagegen_description.md
+++ b/codex-rs/ext/image-generation/imagegen_description.md
@@ -4,7 +4,7 @@ The `image_gen.imagegen` tool enables image generation from descriptions and edi
 - The user wants to modify an attached or previously generated image with specific changes, including adding or removing elements, altering colors, improving quality/resolution, or transforming the style (e.g., cartoon, oil painting).
 
 Guidelines:
-- In code mode, pass the result to `generatedImage(result)`.
+- imagegen needs a few minutes to finish. In code-mode, use the first-line @exec directive to give the initial call 120 seconds and the same yield for any waits that follow. Once it finishes, return the image with generatedImage(result).
 - Omit both `referenced_image_paths` and `num_last_images_to_include` when generating a brand new image.
 - For edits, use `referenced_image_paths` when every target image has a local file path.
 - If you have not seen a local image yet, use `view_image` to inspect it before editing.