What Dex is and how it works

Dex is a personal chief-of-staff that lives on your computer. It plans your day, preps you for meetings, remembers every person you work with, tracks your tasks and goals, and gets more useful the longer you use it — because everything it learns is written into files you own.

There is no Dex app to open and no Dex server anywhere. Dex runs inside Claude Code (or Cursor), an AI assistant you talk to in plain English. Dex is what happens when that assistant is given a memory, a playbook, and a set of tools that turn it from a clever chatbot into a system that actually runs your working life.

That design has a nice side effect: learning Dex is learning how modern AI assistants work. Every skill you pick up here transfers.

The problem Dex solves

AI assistants have a fundamental limitation: they forget everything between conversations. Close the window and tomorrow's session starts from zero — no memory of your projects, your people, or what you decided yesterday.

Dex's trick is simple: store everything in files, and reload the right context at the right moment. Your meetings, tasks, people, and goals live as ordinary text files on your machine. When you start a session, Dex loads what matters. When you mention a person, it quietly pulls up their history. The assistant is stateless; your system is not.

The five building blocks

Everything Dex does comes from five pieces working together. (You can ask Dex to explain any of this live — the /xray command shows you exactly what happened under the hood of your last conversation.)

1. Your vault — files you own

All your data is plain text files (Markdown) in one folder, called your vault. No database, no cloud service, no hidden format. You can open any file, read exactly what Dex knows, and edit it yourself. If you stopped using Dex tomorrow, every note would still open in any text editor — in twenty years, too.

The vault is organized by the PARA method: an Inbox for quick capture, Projects for time-bound work, Areas for ongoing things like people and companies, Resources for reference, and Archives for the past.

2. CLAUDE.md — the standing instructions

One file, CLAUDE.md, is read at the start of every conversation. It tells the assistant who you are, how you like to communicate, and how Dex behaves. In AI terms this is a "system prompt" — instructions that shape every response before you type a word. There's a protected section inside it just for your personal instructions, which survives every update.

3. Skills — the playbook

Skills are packaged workflows you invoke by typing a slash command, like /daily-plan or /meeting-prep. Each skill is just a text file of step-by-step instructions the assistant follows. Dex ships with about two dozen core skills, plus role-specific ones for product, sales, marketing, and more.

Skills load only when you use them — that keeps conversations fast and cheap. And because a skill is only structured text, you can read any of them, change them, or write your own.

4. MCP tools — the reliable hands

Some things shouldn't be left to an AI's best guess: creating a task with the right ID, syncing a completion across five files, reading your calendar. For those, Dex uses MCP servers — small local programs that give the assistant precise, validated operations. (MCP, the Model Context Protocol, is an open standard for connecting AI assistants to tools.)

The rule of thumb Dex is built on: files are knowledge, tools are actions. When Dex creates a task, a deterministic program does the bookkeeping — the AI decides what, the tool guarantees how.

5. Hooks — the quiet automation

Hooks are small scripts that run automatically at certain moments. When you start a session, one shows Dex your priorities and recent patterns. When a file mentions a person you know, another silently injects their context so Dex responds with full history. You never see hooks run — you just notice Dex seems unusually well-informed.

What a session actually looks like

Put it together and a morning with Dex looks like this:

1. You open a session. A hook loads your pillars, goals, and this week's priorities.
2. You type /daily-plan. That skill loads, reads your calendar through the Calendar tool, checks your tasks and priorities, and builds a plan for the day.
3. You mention "the Acme renewal" — Dex quietly pulls the Acme company page and the people involved.
4. Anything you decide gets written back into your vault, so tomorrow's Dex knows about it.

That warning glyph is the whole product in miniature: Dex remembered a promise you'd forgotten, because it was written down.

First, fetch and read the page I'm referring to: https://heydex.ai/help/how-dex-works.md

I just read the Dex Guide page about how Dex works — the vault, CLAUDE.md,
skills, tools, and hooks. You know my role and my vault. Re-teach me those
five building blocks using MY system as the example: show me the most
important lines in my own CLAUDE.md, the three skills that would pay off
most for someone with my job, the tools you can actually reach right now,
and one hook that's quietly working for me. Then tell me which building
block I'm underusing — and set it up with me.

Where to go next

• Installing Dex — get from zero to your first conversation.
• Your first conversation — what Dex asks when you meet, and why.
• Understanding Claude Code — a deeper primer on the engine underneath.
• Prompts to steal — copy-paste moves that use all of this differently.