Picture a reviewer asking an agent to build a 10-slide beginner deck on pour-over coffee. The agent comes back with the slides, plus a note: “By the way, 15 g to 250 g isn’t exactly 1:16.” The agent hadn’t missed anything. The numbers were the ones the reviewer wrote into the brief, and the agent noticed the reviewer had rounded them.
That’s what happened to u/Single-Climate2259 on r/PromptEngineering. Here’s what they did and how you can borrow it.
The Setup: One Blunt Constraint ☕
When an agent writes slides or reports, invented numbers are the thing to worry about most. So the brief listed the only numbers the deck could use, all framed as starting points:
- 1:16 coffee to water
- 15 g of coffee to 250 g of water
- around 93 C
- a 30 to 45 second bloom
- about 3 minutes
Then came one line: no other numbers. Each slide was also capped at 40 words. That’s it. No long style guide, no pages of rules, just a short list and a hard stop.
The run used Sonnet 5.5 with SenseNova-Skills’ slide skills. Those skills include a step for recording where on-screen facts came from. It’s only required for decks built from attachments or research, and this deck had neither. The agent wrote the record anyway and used it to check the rule.
Why It Matters 🔍
If you’ve ever had an AI deck quietly invent a statistic, you know the problem. A made-up “92% of beginners” looks exactly as confident as a real number, and nobody notices until a customer or a boss asks where it came from. A list of allowed values turns “don’t make things up” from a vibe into something you can verify.
The result matters more than the coffee. The agent didn’t just read the constraint. It audited itself against it:
- It searched the slide text and the speaker notes for numerals and found only the five approved ones.
- It listed every slide’s word count, and none went over 40.
- While writing the outline, before any slide existed, it noted that 15 g to 250 g isn’t exactly 1:16. The speaker notes call those figures rounded.
That last catch was the author’s own mistake. The brief had a flaw, and the agent surfaced it instead of silently inheriting it. The same trick works for a sales report, a quarterly update, or a training deck, anywhere a stray figure could cause real embarrassment.
How to Do It Yourself 🛠️
- List the numbers. Write out every figure the agent is allowed to use. Frame them as starting points if they’re approximations.
- Close the door. Add one plain line: “No other numbers.”
- Add a measurable cap. Word counts per slide, items per list, sentences per section. Anything countable works.
- Ask for a source record. Have the agent note where each on-screen fact came from, even if the task doesn’t strictly need it. In this case the record is what the agent checked its work against.
- Ask for the check. Request a numeral search across slides and speaker notes, and a word count per slide. Ask for the results as a short list at the end, so you can scan it in thirty seconds.
Tips and Tricks 💡
Bind each number to its meaning. u/MiserableFlatworm337 made a sharp point. An allowed numeral can still be wrong if a duration turns into a temperature. So write “93 C = water temperature” and “3 minutes = total brew time,” then check those pairs in both slides and notes, not only the raw digits.
Make constraints countable. u/GrossQueen83 notes that length limits for sections work well because agents check them instead of just reading them. If you can count it, an agent can verify it. “Keep it short” is a wish. “Under 40 words” is a test.
Check your own numbers first. The 1:16 versus 15 g to 250 g mismatch came from the human. Do a quick sanity pass on your allowed list before you hand it over. 250 divided by 15 is about 16.7, so “1:16” is a rounded figure, and saying so up front would have saved the agent a flag.
Put the check in the brief. Don’t hope the agent audits itself. Ask for the numeral search and the word counts so the evidence shows up in the output.
Your Turn 🏴☠️
Take your next deck or report brief and add an allowed-numbers list, a “no other numbers” line, and one countable cap. Then ask for the self-check and see what comes back. You might find a flaw in your own brief too.
The original poster asked a good question: what other constraints have you found an agent will actually check itself against, instead of just reading them? Share yours in the comments!
Frequently Asked Questions
Q: Is a list of allowed numbers enough to keep an agent accurate?
Not on its own. One commenter pointed out that an allowed numeral can still end up in the wrong place, like a 93 meant as a temperature showing up as a bloom time. The number is only half the check, so you also need to know what it describes.
Q: How do I check that each number means what it should?
Bind every allowed number to its unit and meaning, such as 93 C for water temperature or 30 to 45 seconds for the bloom. Then have the check compare those pairs across both the slide text and the speaker notes, instead of searching for bare numerals. That catches a correct number used for the wrong job.
Q: Do word limits work better than general instructions for agents?
One commenter who builds their own projects says length limits on sections work well, and that agents actually check a cap like 40 words instead of just reading it. Counting is something an agent can verify with a step, so a hard limit gives it something concrete to test against. That’s one builder’s experience, so spot-check the output yourself for the first few runs.
An allowed-numbers list in the brief kept an agent’s 10-slide deck to my figures, and it flagged that two of them didn’t agree
by u/Single-Climate2259 in PromptEngineering