gecko-mcp

Name: gecko-mcp
Author: Frumane

by Frumaneversion 2.2.4i★ –iRuns on your computer

Registry nameio.github.Frumane/gecko-mcp

Install

Overview

Description from the maker (original English)

Control Firefox browsers (Floorp, LibreWolf, Zen, Firefox) from any MCP client.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
UsageiNot measured yet★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs on your computer
Transport: stdio
Category: Other

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 1 of 1 passed
Runs on your computer with your user’s permissions (files, network, apps).
The registry lists no key to fill in.

You need

npmNode.js installed (for the npx command)

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json

{
  "mcpServers": {
    "gecko": {
      "command": "npx",
      "args": [
        "-y",
        "gecko-mcp"
      ]
    }
  }
}

Run this in your terminal

claude mcp add gecko -- npx -y gecko-mcp

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "gecko": {
      "command": "npx",
      "args": [
        "-y",
        "gecko-mcp"
      ]
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "gecko": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "gecko-mcp"
      ]
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.

Your choice stays on this device in a cookie; no account needed.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 7, 2026

✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account Frumane, which owns the repo
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
– Not applicable
Endpoint responds
This one runs on your computer; there is no internet endpoint
– Not applicable
Sign-in with OAuth
Runs on your computer and uses local settings instead
… Not checked yet
No hidden instructions in tool descriptions
Runs on your computer; we can only read tool lists from internet endpoints

Compared with others in Otheri

More stars than 0% of the other 32599 servers in this category
Published to the registry more recently than 13% of the other 32599 servers in this category
Basic checks equal to or better than 100% of the other 32599 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is gecko-mcp safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

The registry does not list a required key, though some servers ask you to sign in on first use.

Does it run on my computer or in the cloud?

It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed –, and the latest version (2.2.4) reached the registry 5 months ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Node.js on your computer.

What can I use instead?

In the same category: Spec Driven Development, Remote Desktop Commander, Zendesk

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README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

gecko-mcp

An MCP (Model Context Protocol) server that lets AI assistants — Claude Code,

Claude Desktop, Cursor, and any MCP client — **read pages, take screenshots and

manage tabs in [Floorp](https://floorp.app) and other Firefox-based browsers**

(LibreWolf, Waterfox, Zen, Mullvad, Firefox…), using your real, logged-in session.

Think "Claude in Chrome", but for the whole Firefox/Gecko family.

Get started in ~30 seconds:

npx gecko-mcp setup

Registers gecko-mcp with Claude Code, Claude Desktop, Cursor, VS Code (Copilot), Windsurf, Zed, Codex and more — per-project or global. See Setup for manual config and Requirements for the one-time browser step.

Cautious about installing this? Good — you should be. It's small (2 deps, all

in src/), the OS keyboard/mouse is locked by default (browser-only

until you opt in), releases ship with npm provenance (verifiable against this

source), and the full threat model is in SECURITY.md. Read it

before you run npx gecko-mcp.

How it works

gecko-mcp talks to the browser through one of two backends, picked automatically:

Floorp ships a built-in automation HTTP API. Set floorp.mcp.enabled = true in about:config and gecko-mcp uses the fast http://127.0.0.1:58261 API — no extension, richest feature set.
Any other Gecko browser — launch it with Marionette (the automation engine built into every Firefox fork) and gecko-mcp drives your live session over it. Same tools, same real session.

  Claude Code / Desktop / Cursor

│ MCP (stdio) ▼ gecko-mcp ──► Floorp :58261 (built-in API) ─┐ (this project) ──► Marionette :2828 (any Gecko fork) ─┴─► your real tabs

Requirements

A Firefox-based browser installed and running, with automation enabled:
Floorp: set `floorp.mcp.enabled` to true in about:config, restart Floorp.
Other forks (LibreWolf / Waterfox / Zen / Mullvad / Firefox): launch the browser with `-marionette` (see Browser support).
Node.js ≥ 18.

Setup

Quick start — the setup wizard

npx gecko-mcp setup

An interactive wizard registers gecko-mcp with the AI coding tool(s) of your choice — Claude Code, Cursor, Windsurf, VS Code (Copilot), Gemini CLI, Codex, Zed, Cline (and a copy-paste snippet for Kimi Code, Antigravity, or any other MCP client) — and lets you install it for the current project or globally (all repos). It merges into existing config (and backs it up first).

Non-interactive / scriptable:

npx gecko-mcp setup --list                          # show supported tools

npx gecko-mcp setup --tool claude-code,cursor --scope global npx gecko-mcp setup --tool codex --scope global --print # dry run

Manual

Any MCP client works with this server block (no clone/build needed — npx fetches it):

"mcpServers": { "gecko": { "command": "npx", "args": ["-y", "gecko-mcp"] } } }

Or with Claude Code's CLI: claude mcp add gecko -s user -- npx -y gecko-mcp.

One-time Floorp step: set floorp.mcp.enabled = true in about:config and

restart Floorp so its automation API is available.

Browser support

gecko-mcp picks its backend automatically: if Floorp's :58261 API is reachable it uses that; otherwise it connects to Marionette, the automation engine built into every Gecko browser. To use a non-Floorp browser, launch it once with Marionette enabled:

Browser	Launch with Marionette
Floorp	(no flag — just set `floorp.mcp.enabled=true`; uses the native API)
Firefox	`firefox -marionette`
LibreWolf	`librewolf -marionette`
Waterfox	`waterfox -marionette`
Zen	`zen -marionette`
Mullvad	`mullvad-browser -marionette`

Marionette listens on TCP 2828 by default. To use another port, set the marionette.port pref in the profile (e.g. via user.js) and start gecko-mcp with a matching MARIONETTE_PORT. Force a backend with GECKO_MCP_BACKEND=marionette.

Note: Marionette must be enabled *at launch* to attach to your live session.

On the Marionette backend, Floorp-only extras (snapshot fingerprints,

list_workspaces/switch_workspace, accessibility tree) return a clear

"not supported" message — use find / read_page instead. Everything else

(tabs, navigation, click, type, forms, screenshots, cookies, real OS input…) works.

Tools

Tabs & reading

Tool	What it does
`list_tabs`	List all open tabs (title, URL, browserId, active, pinned).
`open_tab`	Open a new tab at a URL; returns the new tab's `browserId` so you can target it.
`get_active_tab`	Return the active tab's title, URL and browserId.
`navigate_tab`	Navigate an existing tab to a URL.
`close_tab`	Close a tab.
`read_page`	Read a tab's content as clean Markdown (or HTML / accessibility tree). Output is capped (default 25 KB) to protect the context.
`find`	Fast element locator — search a page server-side by visible text and/or tag; returns a compact list of ready-to-use CSS `selector`s (~1 KB) instead of the whole HTML. Use it to find a button/link/field, then act on the selector.
`snapshot`	Structured page map: Markdown with inline `fp:` refs + an element selector map — locate elements without grepping HTML, then act via a `ref`.
`screenshot`	Capture a screenshot of a tab (viewport or full page).
`launch_floorp`	Ensure Floorp is running — launches it if the API isn't reachable (Windows).
`launch`	Start any Firefox-based browser (Firefox, LibreWolf, Zen…) with Marionette enabled so gecko-mcp can drive it.

Interaction

Tool	What it does
`click`	Click an element by CSS selector or a `ref` from `snapshot`; auto-scrolls it into view first.
`type_text`	Type into an input/textarea — or a rich/contenteditable editor (Slate, ProseMirror…) — by CSS selector.
`fill_form`	Fill multiple fields at once.
`press_key`	Press a keyboard key (Enter, Tab, …).
`wait_for_element`	Wait for an element to attach / become visible / etc.
`get_value`	Sensitive. Read the current value of an input/textarea/select (can read password fields).

Most tools target the active tab by default; pass a browserId (from list_tabs) to target a specific tab.

OS keyboard & mouse — locked by default 🔒

The tools below can affect things *outside* the browser, so they are disabled until you turn them on. With nothing set, gecko-mcp does browser automation only. Unlock them per-session by just asking ("enable OS input", which calls the enable_os_input tool), or persistently with GECKO_MCP_ENABLE_OS_INPUT=1. Lock again with disable_os_input. While locked, these tools refuse with a clear message.

The `evaluate` tool (run arbitrary page JavaScript) is locked the same way — unlock with enable_evaluate or GECKO_MCP_ENABLE_EVALUATE=1.

Tool	What it does
`enable_os_input` / `disable_os_input`	Unlock / re-lock the OS keyboard & mouse tools for this session.
`enable_evaluate` / `disable_evaluate`	Unlock / re-lock the `evaluate` (run page JS) tool for this session.
`evaluate`	Locked. Run JavaScript in the page and return its value (`return …`).

Real OS keyboard (Windows) — for React/rich editors and bot-guarded submits that ignore synthetic input:

Tool	What it does
`real_type`	Type into the focused element via genuine OS key events (`isTrusted`).
`real_key`	Press a real key/combo, e.g. `"Enter"`, `"ctrl+a"`.
`real_clear`	Real Ctrl+A + Delete — reliably clears a rich/contenteditable field.

These produce input a page can't distinguish from a human's, so they drive React/Slate editors and submit composers that synthetic clicks/typing can't. Workflow: click the field to focus it → real_clear / real_type / real_key "Enter".

Safety guard: OS keystrokes go to the foreground window, so before sending

anything these tools bring Floorp to the foreground and verify it — if Floorp

isn't running or can't be focused, they abort without typing a single key, so

input can never leak into another app.

Real OS mouse (Windows) — genuine isTrusted clicks at screen coordinates:

Tool	What it does
`window_bounds`	Floorp's window rectangle in screen pixels (to compute targets).
`move_cursor`	Move the real OS cursor to a screen pixel inside Floorp.
`real_click`	Real OS click (left/right, single/double) at a screen pixel inside Floorp.

Double guard: the click is sent only when Floorp is verified foreground and

the point lies inside Floorp's window rect — a stray coordinate is refused, so

a click can never land in another app/window. Coordinates are screen pixels

(note display scaling/DPI when mapping from a screenshot).

More interaction & queries

Tool	What it does
`hover` / `double_click` / `right_click`	Mouse gestures on an element (selector or `ref`).
`select_option`	Choose an option in a .
`set_checked`	Check/uncheck a checkbox or radio.
`submit_form`	Submit a form.
`upload_file`	Sensitive. Set a file by absolute path — restrict with `GECKO_MCP_ALLOW_UPLOAD_DIRS`.
`get_attribute`	Read an element attribute (href, value, …).
`get_article`	Readability-extracted main article as Markdown.
`get_cookies`	Sensitive. Cookies visible to the page — values redacted unless `includeValues: true`.
`wait_for_network_idle`	Wait for network activity to settle.
`list_workspaces` / `switch_workspace`	Floorp workspaces (where supported).

Security

Understand the threat model before enabling this. Two risks dominate:

Floorp's automation API has no authentication by default. While floorp.mcp.enabled is on, any local process can drive your logged-in browser via 127.0.0.1:58261 — not just this server. There is also no Origin check, so hostile web pages may attempt CSRF/DNS-rebinding tricks against it. Mitigations:

Turn floorp.mcp.enabled off when you're not using automation.
Set the GECKO_MCP_TOKEN environment variable — this server then sends it as a Bearer token on every request (effective on Floorp builds that enforce a token; harmless otherwise).

Prompt injection ("lethal trifecta"). The assistant reads untrusted page content *and* can act on your authenticated sessions (click, type, submit, navigate, real OS input). A malicious page could try to instruct the assistant to act against you. Treat everything read from a page as untrusted; don't run automation unattended on sites you don't trust.

Hardening built into this server:

OS keyboard/mouse is locked by default (least privilege): the only tools that can act outside the browser refuse to run until you explicitly unlock them (enable_os_input tool, or GECKO_MCP_ENABLE_OS_INPUT=1). By default gecko-mcp can only automate the browser, never your wider machine.
Real OS input is double-guarded: keys/clicks are sent only after verifying Floorp is the foreground window, and mouse clicks must land inside Floorp's window rectangle — otherwise it aborts *without* sending anything. Po

Only the beginning is shown; read the rest in the repo

gecko-mcp

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Otheri

Common questions

Alternatives

Spec Driven Development

Remote Desktop Commander

Zendesk

README from the maker

gecko-mcp

How it works

Requirements

Setup

Quick start — the setup wizard

Manual

Browser support

Tools

OS keyboard & mouse — locked by default 🔒

Security