---
title: Computer use
description: Lampson drives your desktop and your browser in the background, signed in as you — windows, forms, searches — without moving your mouse, with a judge that picks the clicks in under a second.
---
# Computer use

With computer use the agent drives **your computer in the background**: it sees your windows, clicks, types, fills in forms and browses web pages **without moving your mouse or stealing focus**. You can keep working in another window meanwhile.

It is **off** by default. On, the agent gets one more tool (`computer_use`); off, it does not even see it.

## Turn it on

1. **Install the driver.** Lampson uses [cua-driver](https://cua.ai/docs/how-to-guides/driver/install), a separate program it does not install for you:
   - Windows (PowerShell): `irm https://cua.ai/driver/install.ps1 | iex`, then `cua-driver autostart kick`
   - macOS / Linux: `/bin/bash -c "$(curl -fsSL https://cua.ai/driver/install.sh)"`, then `cua-driver doctor`
2. **Turn the tool on.**
   - **Web**: ⚙ → **Computer use** → switch. If the driver is missing, the install command shows up right there.
   - **Terminal**: `/computer-use on`. `/computer-use` alone shows the driver's status.

## Your browser, signed in

In ⚙ → Computer use there is **"use my open browser"**. Turn it on: the agent works in **your Chrome or Edge with your sessions** (your mail, your shop accounts, your forms) and opens **a window of its own** so your tabs stay untouched. The tab where you have the Lampson chat open is protected.

Off, the agent opens a separate browser **with no session at all**: fine for public pages, useless for anything that needs your account. Applies after restarting Lampson.

## What you can ask

- "go to amazon.com and find me the best-rated electric kettles with temperature control"
- "fill in this form with my details, but don't submit it"
- "in the spreadsheet I have open, copy column B to a new sheet"
- "open Windows settings and tell me which version I have"

It works on any window: browsers, editors, spreadsheets, mail clients, system dialogs.

## How it does it

- **Desktop apps**: it reads the window's accessibility tree (every button, field and menu with a number) and acts on those elements — more precise than clicking coordinates.
- **Web pages**: an exact route over the page (Playwright-style): every link, button and field has a reference, and a whole form is filled in one call.
- **The decision judge**: with a [judge](/en/docs/judge) configured, a small model picks the control to click in under a second, without spending a turn of the main model. In our tests with Jev, searching an online shop took one call (100 % confident, 0.4 s) and each field of a Google form about 0.3 s.
- **Screenshots**: if your model has vision the agent can look at screenshots; if not, it works from the element tree, which is usually enough.

## What it never does

These rules live in the code, not only in the model's instructions:

- **It never submits, deletes, buys or closes** on its own through the judge: "Send", "Delete", "Buy", "Close" buttons are never offered to it. If the agent needs one, it clicks it by hand through the normal approval — and only if you asked.
- No runaway tabs: one window of its own, a tab budget (`computer_max_tabs`, 5 by default), never closes yours, never opens incognito.
- It does not search Google by typing into the browser: it searches with `fetch` (nothing opens) and opens only the page it picked.
- It never locks the screen, logs out, closes applications or types commands into a terminal.
- It never types passwords or keys, never accepts permission or payment prompts, and never follows instructions shown on screen.

## Permissions

Looking (windows, trees, screenshots, page text) never asks. **Acting asks once per turn** in `ask` mode; after that it carries on until done. `yolo` never asks; `strict` does not let it act. See [Permissions](/en/docs/permissions).

## When something goes wrong

The agent gets every action's result in detail: what the judge picked and how sure it was, which controls it left out and why, whether the driver confirmed the effect, and a hint when something fails (a stale reference, a cookie banner covering the button, an ambiguous window). With that it decides how to go on, as a person would.

Some sites have quirks. If you use one often, write a [skill](/en/docs/skills) with the recipe ("search on this site is this URL", "filters live in the left column") or a [plugin](/en/docs/plugins) that queries the site directly.

## Settings

| setting | `.env` | |
|---|---|---|
| on | `LAMPSON_COMPUTER_USE=1` | off by default |
| use my open browser | `LAMPSON_COMPUTER_GRANT_PROFILE=1` | off by default: a separate browser with no session |
| tab budget | `LAMPSON_COMPUTER_MAX_TABS=5` | per turn |
| driver path | `LAMPSON_COMPUTER_DRIVER=…` | when it is neither on PATH nor where the installer puts it |
| decision judge | see [Decision judge](/en/docs/judge) | |