How an AI agent uses Form filling and clearing
Fill forms from MCP instructions or the side panel, and empty them again, with field detection and structured values.
Updated · T3rnel Browser 1.3.0
What the agent can do
- Detects visible form controls and maps them to a structured schema an agent can reason about.
- Fills text, selects, checkboxes and radios from a single JSON payload: name a field by its
name, itsidor a CSS selector and give the exact value. Anything you do not name gets plausible generated data, deterministic for a given seed. - Clears a form back to empty in one call, and reports what it cleared and what it skipped. Clearing is not
value = "": React and everything built on the same idea install a value tracker, so a plain assignment is reverted on the next render. This writes through the prototype setter and fires theinputandchangeevents a real edit produces, so the framework state clears with the DOM. - Clearing leaves alone what should be left alone: hidden inputs keep CSRF tokens and form state unless you ask otherwise, ranges and colours return to their declared default because neither has an empty value, a select takes its placeholder rather than silently landing on the first option, and disabled or read-only fields are untouched.
- Says which of your values matched no field, rather than reporting a filled form that is missing the one value you cared about.
- Filling and clearing are classed high-risk: arm the approval gate in Settings and an agent has to be approved before it writes into your page. It never submits the form for you.
The tools
| Tool | Risk | Tier |
|---|---|---|
browser_fill | high | Free |
browser_type | high | Free |
browser_select | high | Free |
browser_form_fill | high | Pro |
browser_form_clear | high | Free |
Calling it over MCP
{ "method": "tools/call", "params": { "name": "browser_fill", "arguments": {} } }Connect a client first: add the MCP Session Bridge. The extension then exposes 97 tools against your signed-in tabs.
Questions
Which tools does Form filling and clearing use?
browser_fill, browser_type, browser_select, browser_form_fill, browser_form_clear.
Is Form filling and clearing free?
Partly. browser_form_fill needs Pro ($29.99 once); browser_fill, browser_type, browser_select, browser_form_clear work on the free tier.
Does the agent have to ask before using Form filling and clearing?
Each tool has a risk level: browser_fill is high; browser_type is high; browser_select is high; browser_form_fill is high; browser_form_clear is high. The approval gate is off by default and can be armed in Settings.