diff --git a/scripts/bgfx.idl b/scripts/bgfx.idl
index 2b53b6262..610e33847 100644
--- a/scripts/bgfx.idl
+++ b/scripts/bgfx.idl
@@ -1880,6 +1880,8 @@ func.updateTextureCube { section = "Textures" }
 --- Read back texture content.
 ---
 --- @attention Texture must be created with `BGFX_TEXTURE_READ_BACK` flag.
+---            It's a texture for CPU readback, and can't be a GPU resource
+---            at the same time. See `examples/30-picking`.
 --- @attention Availability depends on: `BGFX_CAPS_TEXTURE_READ_BACK`.
 ---
 func.readTexture { section = "Textures" }