Browser tasks
With the extension, Harness can do things on a page for you: fill a form, reply to a message, book a slot, work through a site. It works in your own browser, with your own sign-ins, one checked step at a time.
Ask for one
Ask in your own words, in the Harness window or in the prompt on the page: “reply to this”, “fill this form with my details”, “find a table for two on Friday”. If you selected a section first, “this” means that section.
Harness can click, type, choose options, press keys, go back and forward, work across tabs and frames, upload files from your conversation, download files, and handle pop-up dialogs. Each step is checked against the page before the next one.
While Harness controls a tab, Chrome shows its own banner saying the browser is being debugged. That is expected, and it goes away when the task ends.
When it asks you
Harness stops and asks when a choice is yours to make:
- An ambiguous choice. If something could mean more than one thing and Harness is not sure, it asks, for example which account to use or which time to book.
- Downloads from a new site. Downloading from a site the task does not already have open asks Allow or Block.
- Actions a site marks as serious. See Site tools.
Opening a new tab or going to another site follows your Chrome site access: Harness can open sites you allowed the extension to read.
Tabs
A task stays on the page where it started, even when you switch tabs. If a click opens a new tab, the task follows it there. Ask Harness to open something in a new tab and it keeps the current page open and brings the new tab into the same conversation.
Stop a task
Press Stop in the prompt or the Harness window. A stopped task can pick up again when you send a follow-up. Harness also stops on its own when it is blocked, or when three steps in a row change nothing on the page, and tells you why.
Reading linked documents
Harness can read a PDF, Word, Excel, PowerPoint or text file that a page links to, including Gmail attachments. It fetches the file with your existing sign-in, without opening a tab or saving a download. The text is pulled out on your device, and only the text goes to the model. Files up to 8 MB that are linked from the page, or that live on the page’s own site, can be read.
Site tools
Some sites publish actions for agents to use directly (WebMCP), instead of clicking through the page. Turn on Site tools in the extension’s settings to let Harness use them, where Chrome supports them. It is off by default.
- An action the site marks as consequential, or one that moves money, always asks you first.
- An action that is hard to undo runs only if your own words asked for it.
- The answer has to come from you, in your next message. Harness cannot answer for you.
Browser automation
For harder tasks, Harness can write a short program that runs on the page. These programs run in a locked-down space inside the extension with no direct internet access, and they can see more of the page than a normal read. The Browser automation switch in the extension’s settings turns this on or off; it is on by default. It is separate from scheduled Automations.