Prompt Engineering

Why it matters in construction

The same model can give a vague answer to “summarize this proposal” or produce a more useful leveling table when it has clear instructions, a required format, and rules for missing information. The prompt and the documents supplied to the model both affect the result.

For a GC, this matters in two ways. Anyone using a general assistant for precon work can improve the output with a few habits. Anyone evaluating purpose-built software should know that the vendor’s prompt design shapes the product, even when it is invisible.

How it works

A prompt is the full set of text sent to the model, and the useful parts are predictable.

1. Role and task. “You are a senior estimator reviewing a plumbing proposal against the attached scope of work.” This narrows what the model pays attention to.
2. Context. The actual documents: the proposal, the bid package scope list, the relevant spec sections. Without these the model works from general knowledge and guesses.
3. Output format. A table with fixed columns, JSON with named fields, or a bulleted list with a required structure. Fixed formats make output checkable and let software consume it.
4. Rules for uncertainty. “If the proposal does not mention an item, return ‘not stated.’ Never infer an inclusion.” This instruction can reduce unsupported assumptions.
5. Examples. One or two worked examples of a correctly classified line item teach the model the firm’s conventions faster than a paragraph of description.
6. Testing. Run the prompt against proposals where the answers are known, count the misses, and revise. A prompt gets iterated like any other estimating template.

Good vendors version their prompts, test them against labeled document sets, and change them carefully. A small wording change can change the output enough to require retesting.

Example in practice

Consider a precon coordinator at a mid-size GC using a general AI assistant to summarize RFPs before go/no-go. Her first prompt is “summarize this RFP.” She gets three paragraphs of overview and no dates.

She rewrites it: “You are a preconstruction manager. From the attached RFP, return a table with these rows: bid due date and time, pre-bid meeting date, bond requirements, insurance limits, liquidated damages, MBE/WBE goals, and any phasing or occupied-building constraints. For each row, quote the passage and page number. If a row is not addressed, write ‘not stated.’”

The revised prompt returns the 2:00 PM deadline, the mandatory pre-bid on the 8th, a $2,500 per day LD clause on page 41, and a 25 percent MBE goal she had not noticed. The model and document are unchanged; the instructions are more specific.