The more-formal cue is the shipped example of a sentence-scope cue (scope: sentence): instead of enriching single words, it offers up to three more formal rewrites of each whole sentence, which you swap in with the same cycling keys used for word alternatives. Your buffer keeps the original sentence until you explicitly cycle.
What it does
With sentence cues enabled, each sentence you write is offered formal alternatives: thanks a bunch for the help. can cycle to Thank you very much for your assistance. The prompt's contract is strict about meaning: preserve it exactly, add nothing, remove nothing. Its listed moves are the ones you'd expect from a good editor (expand contractions, replace colloquialisms like gonna and touch base, lift casual sign-offs, complete the punctuation), and its avoid-list is just as explicit: no new clauses, no person changes, no question-to-statement flips, no fancy words that distort meaning.
When it deliberately stays silent
The prompt instructs the model to emit a formal cede (ALT: NONE) for anything it shouldn't touch: sentences that are already formal, fragments and one-word acknowledgements (ok.), code and shell commands, URLs, markup, list items, and headers. That cede path is what the project benchmarks hardest: in the five-provider sweep, precision was 100% (150 reject decisions without a single false positive) with recall between 91% and 100% depending on provider. A formality cue that fired on your code blocks would be worse than none.
Cues, not agents
The design point worth understanding: sentence cues are passive. The rewrite never lands in your buffer on its own; it waits as a cycling alternative until you press Ctrl+Alt+↑ on a word inside the sentence, and cycling back restores your original. An earlier prototype that auto-applied the first rewrite was retired precisely because prose was being modified in the background without consent. What ships is offer-only. While a sentence cue's span is active it also wins over overlapping word cues, so you never get a word-level suggestion fighting a sentence-level one inside the same stretch of text.
Enabling and adapting it
Sentence cues are off by default; flip sentence-cues-mode: on in ~/.cues/OPENCUES.md (or via opencues settings _). The cue itself is one file at cues/more-formal/CUE.md with scope: sentence and priority 85, which makes it the template for your own sentence-scope concerns: copy the folder, change the rewrite instruction (more concise, more casual, plainer English), and no code changes are needed. Fair warning from the docs: the current sentence segmenter is regex-based, so unusual abbreviations can split oddly, with the cede path as the safety net.
Related: Rewrite sentences as you type · What is a cue? · Write your own cue · GitHub repo