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Claude Code Production EngineeringStep 5 of 5

Best Claude Code CRO Prompts for Website Optimization

A prompt is only useful if it has a finish line. Nine prompts organised by stage, each stating its mode, demanding observation over inference, and permitting a short answer.

Claude Code Guides: CRO Prompts. Prompt cards arranged in stages.

Why most CRO prompts fail

A prompt list is only useful if each prompt has a finish line. "Audit my landing page for conversion" does not — what comes back is plausible, comprehensive-looking and impossible to act on, because nothing in it is tied to evidence you can check.

Every prompt below does three things the generic version does not. It states which mode it is in, so an audit cannot quietly become a refactor. It demands observation rather than inference. And it permits a short answer, because the alternative is padding.

They are organised by the stage of the work rather than by page type, since the order is what makes them useful.

They assume the method in the conversion workflow, and the general prompt patterns in how to build a website with Claude Code apply here unchanged.

Discovery

Run first, once, and never skip it. Its output makes every later prompt shorter.

This session is DISCOVERY. Change nothing.

Report, from the site itself rather than from assumption:
1. The primary conversion action, and the exact URL where it completes.
2. Every step between arrival and that action, in order.
3. Which steps have a measurement attached and which do not.
4. The platform, and what it decides for us that we cannot change.
5. What you could not determine, and what access you would need.

Then stop and wait.
Eight prompt stages in order: discovery, analytics, funnel, pages, forms, copy, experiments, validation. The first two are highlighted.
The first two are not optional. Everything after them depends on the event count being one.

Analytics verification

Before any number is trusted. This is the prompt that most often stops a project and saves it.

Verify the measurement before analysing anything.

For each conversion event: list every place it can fire, including
theme code, tag managers and installed apps. Then load the page,
complete the action, and report how many times it ACTUALLY fired.

Report the observed count, not the intended one. If the primary
conversion event fires zero times or more than once, stop and say
so — no downstream analysis is valid until that is fixed.

Funnel diagnosis

Map the funnel and find the worst step.

For each step: the number entering, the number continuing, and the
proportional drop. Segment by device before drawing any conclusion —
report mobile and desktop separately and say if they disagree.

Identify the largest PROPORTIONAL drop, not the largest absolute
one, and name the page or component that owns it.

If a step has no number attached, say so and treat it as the
finding rather than estimating it.

That last instruction matters more than it looks. Asked to produce a funnel, a model will happily produce plausible numbers for steps that were never measured, and the result is indistinguishable from a real one.

Product and landing pages

This is an AUDIT of . Change nothing.

Complete the page's primary action yourself, as a new visitor with
no cookies, at 375px and at 1280px. Report what you observed.

Then produce findings, each with:
  the URL and component, what you observed, the conditions,
  why it costs conversions, and a label:
    proven problem | strong heuristic | experiment opportunity |
    insufficient data

Order by impact and confidence over effort. Put proven problems
first regardless of size.

If there are only three findings, return three. Do not pad.

The four labels are the load-bearing part. Without them everything arrives in the same confident register and the reader cannot separate the reproduced bug from the hunch.

Forms

Audit every form on the conversion path.

For each field: is it required, and can you state what it is used
for and what breaks without it? List any field that fails that test.

Then test mechanically and report what happened:
  submit with a valid value; submit with an invalid one;
  submit with JavaScript disabled; navigate it by keyboard only.

Specifically report: whether errors are associated with their
fields programmatically, whether a failed submission preserves
what was typed, and whether there is a visible success state.

Copy

Audit the copy on  against what it must do.

For each claim: is it specific enough to be falsifiable, or is it
an adjective? Quote the ones that are adjectives.

List the objections a sceptical buyer would raise, in the order
they would arise, and say whether the page answers each one BEFORE
that point.

Do not write replacement copy in this pass. Do not propose adding
testimonials, customer counts, ratings or any other proof that does
not already exist — if the honest answer to an objection is "we
have no evidence", that is the finding.

Experiments

The most valuable output of this group is frequently "do not test this".

Before designing any test, work out whether it can be powered.

Given the baseline conversion rate and the weekly traffic to this
step, calculate the sample size needed per arm to detect the
smallest effect worth acting on, and how long that would take.

If the answer is longer than about six weeks, say so plainly and
recommend shipping the change on its reasoning instead, with the
expected direction written down beforehand.

Do not predict a percentage lift. If that could be known in
advance there would be no reason to run the test.

Validation

This is VALIDATION of the change shipped on .

State what was expected to move, and what actually moved, over the
same window before and after.

If several changes shipped together, say that the effect cannot be
attributed to any one of them, and do not attribute it.

A verdict of "cannot tell from this data" is a valid and expected
outcome. Prefer it to a confident answer the data does not support.

Making them reusable

Prompts pasted from a page decay: the constraint you stated once gets forgotten twenty messages later, and the next session starts without it.

Two things fix most of that. Put the standing rules — audit mode changes nothing, findings carry evidence, no predicted lifts, no manufactured urgency — in CLAUDE.md, where they apply to every session without being restated. And keep the per-task prompts as files in the repository rather than in a notes app, so improving one improves it everywhere.

The production CLAUDE.md guide covers the first, and the prompt patterns guide covers why a constraint stated once in a long session stops being followed.

Read these next

See how this fits into Claude Code Production Engineering

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The CLAUDE.md Starter Kit, free

Four working CLAUDE.md files you can drop into a project today, plus the one-page checklist for what belongs in one and how to tell whether yours is actually working.

  • CLAUDE.md for a static marketing site
  • CLAUDE.md for a web application, with security and migration rules
  • CLAUDE.md for a Shopify theme, including the gotchas that cost hours
  • CLAUDE.md for a shared package in a monorepo
  • A one-page checklist, and how to test the file is actually working
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