Thanks for the response. I agree that specificity is important.

I provided a few specific clues and answers along with the grid layout, and a theme as context. Ideally this would generate a filled crossword that I could then verify and edit.

Claude would churn, restarting from scratch over and over trying to fill the layout. If I remove the grid layout from the context, I can generate sparse sequences like you mention but these are not very fun to play.