Specify the format
- prompting
- format
Format is the shape of the output: a table, a numbered list, three paragraphs, a slot-filled template. Every answer arrives in some shape — the only question is whether you chose it or the model did. If the text will be pasted into a document, compared with other answers or read by a skimmer, choose it.
Why shape matters
- Downstream tools need structure. Columns feed spreadsheets; keys feed scripts; headings feed reports.
- Comparisons need alignment. Five vendors in prose cannot be scanned; five rows in a table can.
- Reviewers need the rhythm. A manager skims bullets, not paragraphs.
How to specify it
Name the structure, then its contents:
- The kind — “a table”, “a numbered list”, “exactly three paragraphs”.
- The fields or columns — “columns: vendor, price, setup time, main risk”.
- The limits — “maximum 15 words per cell, six rows, sorted by setup time”.
- The template, when it is strict — paste the skeleton and say “fill this in”.
A template is the strongest format instruction there is: fill-in-the-blank leaves almost no room for tokens to wander. When you need several shapes from the same material, ask for the skeleton first, approve it, then have it filled — that is prompt chaining, one wave away.
A bad example
Ask: “Compare these five vendors.”
You get five paragraphs of prose — pleasant to read once, impossible to scan, sort or paste anywhere.
A better example
Ask: “Compare the vendors below in a table with columns: vendor, price, setup time, main risk. One line per cell, maximum 15 words. Six rows at most, sorted by setup time.”
The reply lands in the shape your decision needs, and every weakness is visible as a wrong cell.
Why it works
Structure is a constraint — and constraints narrow the plausible space. It also moves review earlier: with a stated shape, a wrong answer is obvious at a glance instead of hiding inside good prose. The best part: the format line is copy-paste reusable. Once you have “columns: X, Y, Z; max 15 words per cell”, it survives every future comparison task.
Formats travel: a table pastes into a document, a checklist gets walked through in a meeting, a labeled list scans in seconds. Choosing the format is choosing who can use the result without rework — say it in the prompt, and the last mile of the work disappears.
Practice
Fix the unstructured summary
A teammate needs customer feedback summarized for a product meeting, but wrote a prompt that will produce prose — impossible to scan or paste into the minutes.
Rewrite the prompt so the output arrives in a usable shape.
The weak prompt
Summarize the customer feedback for the product meeting.
A strong version (self-assessment — not machine-graded)
Summarize the customer feedback below for a product meeting as a table with columns: theme, frequency (number of mentions), one example quote, suggested priority (high/medium/low). Maximum six rows, sorted by frequency, maximum 15 words per cell. No commentary outside the table.
Hint
Where will this text go next — and what shape does that place need?
Why this is the answer
The fixed prompt turns “a summary” into a specific artifact: a six-row table with named columns, limits and an ordering rule. Format is a constraint — and stated constraints make weak answers visible at a glance instead of hiding inside good prose.
Transfer
- Meeting summaries: table with decisions, owners, deadlines.
- Research: one line per source — claim, evidence, confidence.
- Anything heading to a spreadsheet: name the columns, then the rules.
Key takeaways
- Name the kind, the columns or fields, and the limits.
- A filled template is the strongest format instruction available.
- The format line is reusable — it survives every future comparison task.
Next
Next: Examples and few-shot — teaching a pattern with examples instead of adjectives. The prompt glossary entry is the one-line version.