Compare two documents

Comparison prompts drift into summarizing both sides. This one forces the differences that actually matter.

When to use it

Contract redlines, spec revisions, config diffs — anywhere the question is “what changed that I actually have to care about”.

What it prevents

A summary of both documents. Comparison prompts drift into description. Restricting the output to differences that change an obligation is what keeps it useful.

The prompt

Compare the two contract clauses below and report the differences that change our obligations.

### Output format
A markdown table with three columns: what changed, the practical effect on us, and the risk if we miss it.

### Requirements
- Report only differences that change what we must do, pay, or deliver. Ignore rewording.
- Quote the exact phrase that changed in each row.
- If a difference is ambiguous, say so rather than picking a reading.

### Clauses
"""
A: Payment within 30 days of invoice.
B: Payment within 30 days of acceptance, acceptance deemed to occur on delivery.
"""

Why each part is there

Every section of that prompt exists because a specific failure happens without it. These are the checks it passes, and what each one is protecting you from:

• States a concrete task — why this matters
• Avoids vague language — why this matters
• Specifies an output format — why this matters
• Avoids dangling references — why this matters
• Separates data from instructions — why this matters
• Avoids over-aggressive phrasing — why this matters

How to adapt this one

Swap in your two versions and keep the framing tight: “only differences that change what we must do, pay, or deliver — ignore rewording”. That filter is the prompt. Comparison drifts into describing both documents unless you forbid it, and a redline that lists every changed comma buries the one clause that shifted a deadline in a wall of cosmetic diff.

The mistake this prompt avoids

Getting a summary of both documents instead of the delta. Asked to compare, a model narrates each side in turn and leaves you to spot the difference yourself — which was the job you were outsourcing. Restrict the output to what changed and what it obligates you to do. A comparison that is not about the differences is just two summaries stapled together.

A variation

Diffing config or code rather than prose? Ask for the differences grouped by blast radius — “which changes affect runtime behaviour, which are cosmetic” — instead of a flat list. A textual diff already tells you every line that moved; what you need is which of those moves can take down production, and that judgement is the part a plain diff cannot give you.

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