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#5 With AI, Development Shifts From "Writing" to "Defining" — This Week's AI Tool Report

January 19, 2026

Hi, I'm Hattori from coiai. This time I want to share the effective ways of using AI tools, and the shifts in development style, that I've noticed after trying out a bunch of different AI tools this week .

1. Splitting coding duties between "Cursor" and "Claude"

The two coding LLMs I mainly used this week were Cursor and Claude .

I used to rely on the autonomous AI engineer "Devin," but these days I've mostly switched over to Cursor for the better balance of cost-performance and accuracy .

2. Blazing-fast slide generation with "Marp" × "LLM"

Since LLMs are so good at handling text, document creation can get dramatically more efficient with the right approach .

My favorite discovery lately is combining Marp, which converts Markdown into slides, with an LLM . Just have the AI write a requirements document in Markdown, then format it into Marp, and a several-dozen-page proposal or spec document is done in an instant . Gemini's canvas feature is great too, but for generating large slide decks in one go, this "manage everything as text" approach is extremely powerful .

3. Networking knowledge with the note-taking tool "Obsidian"

I'm also making use of Obsidian, another note-taking tool that manages everything in Markdown . By linking notes together with hashtags and visualizing the connections, you can see where your own interests are gravitating, almost like looking at a "city" of connected ideas . It pairs well with AI too, making it ideal for the work of connecting knowledge together .

4. The engineer's joy is shifting from "writing" to "making"

AI used to give you the feeling of "building something together," but now it's entering a stage where it "does the whole thing completely" .

Because of this, the pure joy of programming itself might fade a little, but I feel that in its place, **the joy of building things at breakneck speed is what's taking over . Going forward, the emphasis will keep shifting away from "writing code" and toward "requirements definition" — correctly instructing AI on what to build**, and that shift will only get bigger .


A note from us Alongside XR development and web app development, coiai also builds "on-premise AI" that keeps the risk of confidential information leaks to a minimum. If your company wants to safely have AI learn from your internal documents, please get in touch through "coiai.net" .