I am a developer. Sometimes we have stories which will require some sort of asset that is not in the control of the dev team. A common example would be that the story calls for a new piece of UI to be added, but another party/department will be providing the correct copy (text) for this.
I may be told the requirements for a new story are something like:
"We need to add something across the top here. It'll be no more than two lines of text and maybe 5 bullet points. It needs to look prominent and visually interesting."
At this point, I have no idea what the copy will actually be, but need to size the story anyway, based on what I think it roughly entails. When it comes to sprint planning, the story is pulled into the sprint and often I am told the copy will be ready by a certain day, which falls during the upcoming sprint itself. So the story is entered into the sprint with a size, but without the assets available.
I find these stories often take me longer than I estimated, or I put off starting them because the assets aren't ready yet and I don't know when they will be. Sometimes the sprint ends and the assets still weren't available for me to start.
If I need to do some design work it sometimes takes twice as long it should because I don't really know what content I'm designing for. Other issues that crop up are things like I start the story and finish the UI, but then the copy becomes available. So I need to revisit the story and enter the copy. Then I might need to work on it again to make it look right now that the final copy is in. All this time I can't really mark the story as Done and this kind of story sitting in "In Progress" for days half finished clutters my mind and affects my focus on another area of development.
I feel like no story should be entered into the sprint unless all the assets are finalised and available. Is this an unrealistic expectation? We are a small company and don't really have a dedicated Scrum Master - it's basically me, but as I am also a developer and don't necessarily have time to be chasing for assets during a sprint (and I find it distracting).
What should we be doing?