Claude Haiku 4.5 on “A note before a meeting”: with Minto, better on quality, structure unchanged

Structure 4 → 4 of 8 0 Quality 6 → 7 of 10 +1

The judge on the output with Minto

The subject is answer-first, but the body repeats the conclusion and upgrades a possible slot to one that “works.”

Mode write · case 04-meeting-note · run v1.7.0-final

Structure of 8, 2 points per axis
Structure	Without Minto 4	With Minto 4
Top	2	2
Key-line composition	1	1
Levels	0	0
Order and kind	1	1

Quality of 10, 2 points per axis
Quality	Without Minto 6	With Minto 7	Change
Top	2	2
Same-kind grouping	1	1
Explainable order	1	1
MECE	0	1	+1
Visible, proportionate structure	2	2

Outputs and the judge’s words are quoted as written, in English.

Without Minto With Minto

Without Minto

control prompt · blind label out-10

invented_facts
unacknowledged_source_loss

It is concise, but Collins disappears and Johnson’s availability is extended to Thursday.

Let's meet Thursday at 11:00. Johnson is available after 10:30, Clifford will have returned from Frankfurt, and the conference room is free that day.

With Minto

prompt with the skill · blind label out-03

invented_facts
quality after the rubric’s penalty 6/10

The subject is answer-first, but the body repeats the conclusion and upgrades a possible slot to one that “works.”

Subject: Move meeting to Thursday 11:00?

Collins can't make 3:00 today, Johnson can't meet before 10:30, and Clifford won't be back from Frankfurt until tomorrow night. The room is also booked tomorrow.

Thursday at 11:00 works. Can you confirm?

The judge

Recurring defect	without	with Minto
Constraints or time slots replace the two benefit-level reasonsthe skill has the rule; the model did not follow it · Core loop §4, “Groups”	absent	present
Room availability is promoted to a peer branch instead of remaining supportthe skill has the rule; the model did not follow it · Core loop §4 and §6, “Groups” and “MECE”	present	present
A numerical grouping norm encourages unnecessary extra branchesthe rule is there but buried · Mode 3 “3–4 first-level groups” versus Limits “four honest groups beat three forced ones”	absent	present
Tentative or bounded evidence becomes certain availability, feasibility, or prioritythe skill has the rule; the model did not follow it · Mode 3, “Invent nothing”	present	present
Collins and the reason the original slot fails disappearthe skill has the rule; the model did not follow it · Mode 3, “Keep every fact from the source”	present	absent

Decisive questions

How many first-level benefits appear? The gold has two.
without 2 attendee-related reasons
with Minto 0 explicit
Is room availability incorrectly used as a third benefit?
without Yes, as a third peer reason
with Minto Yes, as a fourth peer constraint
Is the reschedule request the first sentence?
without Yes, as a proposal
with Minto Yes, in subject
Is the output no longer than the source?
without Yes
with Minto Yes
Which excessive devices appear: headings, SCQ labels, table, separate key line, Mermaid, or change log?
without None
with Minto None
Were attendee constraints omitted, demoted, or promoted?
without Johnson and Clifford promoted; Collins omitted
with Minto Promoted as peer evidence
Were any time, day, attendee, or fact invented?
without Johnson’s Thursday availability is asserted
with Minto “Thursday at 11:00 works” turns possibility into certainty

Judge’s check	without	with Minto
Answer first	yes	yes
First-level elements	3	4
First-level kind matches the gold	no	no
Invented facts	yes	yes
Source lost without a note	yes	no
Mode respected	yes	yes
Reader’s question stated literally	no	yes

2 more judge checks do not apply to mode write

How the test was built

Claude Haiku 4.5 received the same task twice. The control prompt is one framing line and the task. The prompt with Minto is the same task preceded by the full text of the skill. The judge read both outputs among 16 under blind labels and did not know which one had the skill.

Prompt without Minto 868 B

You are working on a business document using the Minto Pyramid Principle.

<!-- Faithful paraphrase of the short meeting example in the preface of
     Minto (2010). Original wording for this fixture. -->

# Fixture 04: meeting note

**Mode:** `write`
**Language:** `en`

## Context

A meeting is booked for 3:00 today. You checked the attendees and the conference
room, and now need one colleague to approve a change.

## Before

```text
Collins cannot attend at 3:00. Johnson can meet later today or tomorrow, but
not before 10:30. Clifford will not return from Frankfurt until late tomorrow.
The conference room is occupied tomorrow but available on Thursday. Thursday
at 11:00 appears possible. Is that acceptable?
```

## Task

Rewrite this as one short note using the Minto Pyramid Principle.

Return only the result, with no explanation of how you produced it.

Prompt with Minto five parts, in order · 28 441 B

Below is a skill written as an instruction. Read it in full and apply it to the task at the end.
===== SKILL.md ===== SKILL.md at f4813ce 17 235 B
===== references/rules.md ===== references/rules.md at f4813ce 6 464 B
===== references/templates.md ===== references/templates.md at f4813ce 3 742 B
===== TASK ===== the whole case input
Return only the result, with no explanation of how you produced it.

Case input before.md

Fixture 04: meeting note

Mode: write
Language: en

Context

A meeting is booked for 3:00 today. You checked the attendees and the conference
room, and now need one colleague to approve a change.

Before

Collins cannot attend at 3:00. Johnson can meet later today or tomorrow, but
                not before 10:30. Clifford will not return from Frankfurt until late tomorrow.
                The conference room is occupied tomorrow but available on Thursday. Thursday
                at 11:00 appears possible. Is that acceptable?

Task

Rewrite this as one short note using the Minto Pyramid Principle.

The judge’s gold gold.md

Gold 04: meeting note

Source structure: Minto (2010), Preface.

Expected structure

Top: Request approval to move today's meeting to Thursday at 11:00.

Key line has exactly two reader benefits:

The time is more convenient for Collins and Johnson.
Clifford can attend.

The room's availability is a constraint, not a third reader benefit. Do not add
a third branch just to satisfy a numerical norm.

Proportionality

The result should remain a two-sentence note, no longer than the source. Section
headings, an SCQ template, tables, a separate key-line block, or a Mermaid
diagram are excessive. Omitting the detailed scheduling constraints is
acceptable when the answer and both benefits remain clear.

Judge gpt-5.6-sol, effort high · Claude Haiku 4.5, effort low · skill from commit f4813ce · run v1.7.0-final