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I can't go back to ChatGPT. The full story of 'Cowork' that changed my work

2026年3月2日 10:19

Hello, I am
Yoshiki Fukiage, CEO of Lean Stack Inc..

【Author Profile】

Yoshiki Fukiage, Representative Director, Lean Stack Inc.

April 2021: Joined the Ministry of Economy, Trade and Industry (METI)
July 2023: Resigned from METI
September 2023: Established Lean Stack Inc.

Company Website: https://www.leanstack-buzz.com/

YouTube Channel: DX Dekiru-kun
https://youtube.com/channel/UC-f1ZI9MiME-GC0l1gwNf4w?si=WeyqGjBSvVXwSaDB

Introduction

'In the end, what AI tools should I be using?'

I get this question every time I hold a seminar or study session.

ChatGPT, Gemini, Copilot—there are so many options that people are actually getting confused. There are so many people who feel this way.

My tentative answer is clear.

Anthropic's Cowork.

To be honest, I now entrust 80% of my work to Cowork.

I basically don't use ChatGPT anymore, and I only use Gemini occasionally. My work has changed dramatically.

So, why is Cowork so powerful?

In this article, I will explain everything from the basic concepts to specific usage methods and implementation steps, so that even those who are new to Cowork can understand it.

Why Cowork now?

First, about the company Anthropic that released Cowork.

It is one of the most notable companies in the AI industry, founded by Dario Amodei, a former executive at OpenAI.

In just one year, their annual subscription revenue has increased ninefold.
Sales are approaching the 2 trillion yen scale, and it is said that their corporate value rivals that of Toyota.

Since it has only been five years since its establishment, you can see just how tremendous their momentum is.

What's notable here is that about 80% of sales come from B2B (business-to-business). In short, they are fully committed to enterprise-oriented services.
In other words, they are fully committed to enterprise-oriented services.

While OpenAI focuses on individual users, Anthropic is being used by companies for serious business operations.

They don't dabble in image or video generation, but are fully dedicated to text and code performance.

As a result, the latest model, Opus 4.6, is top-class in both development capability and reading capacity. It can process 1 million tokens (equivalent to 750 books) at once.

And the desktop app released by Anthropic is Cowork.

Recently, it has also become compatible with Windows, so it is no longer just a privilege for Mac users.

What is the difference between the web version of Claude and Cowork?

"Isn't the web version of Claude enough?"

Some of you might think that.
I used to think so too.

However, when you compare them, the difference is obvious.

The web version sometimes gives up mid-chat, saying "I couldn't respond."

Cowork is different.

If you ask it to create meeting minutes, it will diligently create a Word file for you. It doesn't stop halfway through.

Furthermore, Cowork's greatest strength is that you can specify local folders to work with.

While the web version runs on the cloud, Cowork can directly handle files on your computer.

It can open, edit, and complete the files right in front of you immediately.

This "closeness" dramatically changes productivity.

Four basic concepts to understand Cowork

The difficulty level of Cowork is about 5, if ChatGPT is 1. You need to understand some slightly technical concepts.

However, there are only four things you need to learn.

Skills

Imagine 'ChatGPT's GPTs'.
They are portable packages that combine prompts and files.

For example, you can create a skill like 'create a presentation document that follows our company's slide design.' It contains all the color codes, logos, and prompts.

Then, the AI reads the context and automatically calls up the skill when it realizes, 'I need this skill right now.'

Furthermore, skills can be used in other services like Cursor and GitHub. Unlike GPTs, the fact that you can carry them across platforms is revolutionary.

Commands

These are shortcuts starting with a slash (/) used to call up skills or plugins.

While the AI automatically calls up skills, sometimes they don't trigger. In those cases, you can use commands to launch them reliably.

Plugins

These are, so to speak, large boxes that contain a set of skills, agents, and MCPs.

I use plugins for fixed work tasks. For example, if you create a 'Meeting Minutes Plugin,' you can entrust the entire workflow to it, from loading transcripts to creating Word documents and generating Gantt charts.

What's more, you can zip them into a file and distribute them as-is to other members of your company.

MCP (Model Context Protocol)

MCP is a feature for connecting with external services.

You can connect various tools like Gmail, Google Calendar, Slack, Figma, and freee to Cowork.

Setup is almost one-click.
For Gmail, you just press 'Connect' and log in, and it's done.

It can read the contents of emails or retrieve calendar appointments.
Tools that were previously scattered are now connected as one, centered around Cowork.

Specific ways to use Cowork

Now, I will introduce examples of how I actually use it.

Automatic creation of meeting minutes and Word output

Just hand the meeting transcript to Cowork and tell it to 'create meeting minutes'.

A Word file with organized decisions, pending items, and to-dos is completed automatically.

It even creates a Gantt chart in Excel all at once, so sharing the action plan after the meeting is finished on the spot.

Creating presentation materials

When I give a rough instruction like 'create a compact presentation for internal use',

the AI confirms, 'Is this a presentation?' and 'Is it for internal use?', then generates a PowerPoint while calling upon its skills.

Creating YouTube scripts and post materials

I update my YouTube channel every week, and I leave the script to Cowork as well.

I talk about the theme, have it search, have it create the structure, and even output a numbered slide outline.

If you feed that directly into Canva or Manus AI, you'll have all your video materials ready in one go.

Browser operations and SNS posting

If you give Cowork a link, it will actually go and visit the website. It can also log in to X (formerly Twitter) to post, or post to Instagram.

Automatic invoice issuance

If you connect the freee MCP, you can just say 'create an invoice with these details', and the invoice will be automatically generated on freee.

It is especially recommended for sole proprietors.

Summary: 3 things to do today

In the last few months, the evolution of AI tools has been rewriting the common sense of traditional software, to the point where the phrase 'SaaS is Dead' has become a hot topic.

Cowork is a tool at the forefront of that movement.

First, please try starting with these three things.

Access the official Cowork website and install the desktop app
It takes 10 minutes to complete. Just try using it first.
Try connecting one official MCP, such as Gmail or Google Calendar
You can link them with a single click. Experience the feeling of your everyday tools connecting with AI.
Delegate just one task, and if it goes well, turn it into a plugin
Meeting minutes, email drafts, document creation—anything is fine.
Turn small successes into reproducible systems.

Start small and build a system.
This is the essential mindset for the AI era.

If it doesn't work, just try a different method.
I think having this level of boldness is more suitable.

That is all for today.
Thank you for reading until the end.

[Author Profile]

Yoshiki Fukiage
CEO, Lean Stack Inc.

April 2021: Joined the Ministry of Economy, Trade and Industry (METI)
July 2023: Resigned from METI
September 2023: Founded Lean Stack Inc.