✓ Free · MIT License Manufacturing Healthcare

A3 Coach

Build a complete Toyota A3 problem-solving report in a single Claude session: all eight sections, from Background to Follow-up Actions. Improvement projects that live in people's heads, buried in email threads, or never reach leadership get a clear written analysis and a document to stand behind.

⬇ Download Skill The 8 sections ↓

What an A3 Is (and Isn't)

A structured story that fits on one page.

The A3 is named after the ISO paper size. The idea is that a complete problem-solving analysis fits on a single sheet. That constraint is intentional: it forces clear thinking. An A3 that sprawls into a slide deck or a multi-page memo has failed the format.

The A3 is a thinking aid, not a reporting form. The act of completing it, especially the current condition → goal → root cause sequence, is where most of the learning happens. The document is a record of that thinking.

The most common misuse

Filling in the sections backwards: writing countermeasures first and retrofitting a root cause to justify them. The eight sections have a sequence. Jumping to section 5 before completing section 4 produces an A3 that looks finished but doesn't hold up in a review.

The 8-Section A3 Grid

Left side: understand the problem. Right side: solve it.

The left side (sections 1–4) must be genuinely complete before the right side begins. This is the discipline the A3 format enforces.

← Left Side: Understanding the Problem (Sections 1–4)

Background

Why this problem, why now. The business or operational context that makes it worth solving. One to three sentences, enough to tell a reader unfamiliar with the area why they should keep reading.

Current Condition

What is actually happening, in specific and measurable terms. A sketch of the process, the data, and the gap. Not what we think is happening, but what was observed.

Goal

The specific, measurable target condition. Written after the current condition is understood, not before. Answers: what will be true when this is solved, by when, measured how.

Root Cause Analysis

The mechanism that produces the gap. Usually a 5-Why chain or a cause-and-effect diagram. The root cause is the one where addressing it prevents recurrence, not just the nearest upstream factor.

Right Side: Solving It (Sections 5–8) →

Countermeasures

The specific actions that address the root cause, not symptoms. Each countermeasure links back to a finding in section 4. Owners and timing live here.

Implementation Plan

Who does what by when. A simple action register with owners, due dates, and status. Detailed enough to hold people accountable at a weekly review.

Effect Confirmation

How we will know the countermeasures worked. The metric from section 3 measured again after implementation. A trend chart if the data supports one.

Follow-up Actions

What needs to happen to hold the gain: standard work updates, training plans, audit schedules. What related problems were surfaced that need a new A3.

The Two Sides

Left side is not a warmup. It is the work.

Left Side: Sections 1–4

Understanding

Background, current condition, goal, and root cause. Most A3s fail here. Either the current condition is vague, the goal is written before the condition is understood, or the root cause is a symptom. The A3 Coach prompts for observations and data at each step and flags sections that are thin before moving on.

Right Side: Sections 5–8

Solving

Countermeasures, implementation plan, effect confirmation, and follow-up. These sections are only as strong as the left side. A crisp root cause produces countermeasures that are specific and testable. A vague root cause produces countermeasures that feel plausible but don't stick.

Common A3 Mistakes

The three ways an A3 fails before it leaves the room

Jumping to countermeasures before root cause

Section 5 filled before section 4 is finished. Countermeasures written this way address symptoms. The problem recurs, and the A3 author looks like they missed something they did not miss.

Writing the goal before the current condition

The goal must be derived from the current condition data. A goal written first is a wish, not a target. It cannot be validated in section 7 because there's no baseline to compare against.

Making it longer than one page

When an A3 runs long, it means the thinking hasn't been compressed. Longer is not more rigorous. It's an unfinished edit. The constraint is the discipline. The skill will flag any section that is becoming a paragraph where a sentence would do.

How It Works

Describe the problem. The skill coaches you through.

Describe the problem in plain language

No structure needed. Tell the skill what's going wrong, where, and how often. A single paragraph is enough to start. The skill asks follow-up questions to fill gaps rather than waiting for a complete briefing.

The skill drafts the left side and checks it

Background, current condition, and goal are drafted from what you gave it. The skill checks whether the current condition is data-backed and whether the goal is measurable, and asks for what's missing before moving on.

Root cause analysis: 5-Why or fishbone

The skill runs a 5-Why chain in conversation or builds a cause-and-effect diagram from the factors you identify. It distinguishes the root cause from contributing factors and labels each clearly.

Right side: countermeasures linked to root cause

Each countermeasure in section 5 is tagged to the finding in section 4 it addresses. Implementation plan includes owner and due-date placeholders. Effect confirmation specifies the metric and the check date.

Export-ready document

The completed A3 is delivered as a formatted Markdown document, ready to paste into Word or a tier board template. The skill calls out any section that still needs data from the gemba.

Examples

Manufacturing and clinical problems both supported

🏭 Weld Defect Rate

🏥 Lab Turnaround Time

A weld defect rate running at 4.2% against a 1.5% target. Two shifts, one cell. The operator described the problem in two sentences. The skill built the current condition from shift data pasted as a table, ran a 5-Why that traced the root cause to a setup parameter not included in the standard work, and produced countermeasures pointing to a standard work update and a one-point lesson for the setup crew.

Root cause reached

Why → why → why → why → the parameter range for gas flow was documented in the equipment manual but never transferred to the station's standard work sheet. Countermeasure: update standard work and verify at next audit.

Lab specimen turnaround time averaging 68 minutes against a 45-minute target for STAT orders. The skill uses clinical vocabulary throughout ("specimen," "collection," "order," "provider") and adapted the current condition section to show the elapsed time broken down by sub-process rather than a manufacturing process map.

Healthcare note

For clinical A3s, the effect confirmation section specifies both the metric and the data source, whether EHR timestamps, manual log, or observation, because "we'll check next month" is not a confirmation plan.

What you get

A real run on the sample data

Unedited output. The sample message at the top went to Claude Sonnet 4.6 (an earlier-generation model, so a newer one may word things differently) with this skill pasted in, the same way the steps below show, on September 29, 2026. Scroll inside the frame to read the whole reply.

Open the full image

Installation

Describe the problem. Get the A3.

Copy the skill. Open a3-coach.md, select all the text and copy it.

Paste it into Claude. In claude.ai, start a new chat and paste it as your first message, or paste it into a Project's instructions so it's there every time. The free plan works, and free accounts can keep up to five Projects.

Say what's in front of you, in your own words, with any data you have (leave out names). Try "build an A3 for [problem]," or just describe what's going wrong, where, and how often. Add "just draft it" to skip the questions and get the whole deliverable now.

See a finished example first (optional): the worked examples are in the download, in the resources/examples folder.

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