agentfenster

agentfenster MCP server

The agentfenster MCP server lets Claude Code and other MCP clients drive real Windows applications on a hidden second desktop inside your own session, with the same logins, cookies and VPN, while you keep your screen, mouse and keyboard. It is a local stdio server with 11 tools, from a one call task loop down to single verified clicks.

Every action is verified against the window state afterwards. A click that lands nowhere is reported as a failure, never as a silent success.

Full documentation: https://agentfenster.com/mcp

The MCP server ships with the agentfenster app, a commercial closed-source Windows product. This repository is its public documentation and issue tracker. It contains no product source code.

Install

1. Install agentfenster on Windows 10 or 11 from https://agentfenster.com. The MCP server is part of the app. Every plan starts with a 3-day trial, no card and no account required.
2. Register the server with Claude Code:

claude mcp add agentfenster -- agentfenster-mcp

Any MCP client that can launch a local stdio server works the same way. Then just ask:

> open the character map on the agent desktop and turn on the advanced view

The 11 tools

Tool	What it does
list_windows	Lists the windows this machine can drive, with title, class, minimized state and whether a picture can be captured. The starting point when you do not know the exact window title.
desktop_task	Runs a full GUI task in one window and returns a single paragraph: what happened, whether it worked, and if not, which step failed and why. The click loop runs inside the server, so its retries never enter your context.
inspect_window	Returns the capped, filtered element tree of one window as a compact list, for planning clicks yourself. Capped at 200 elements and never walked from the desktop root.
replay	Lists recent runs, or returns one run's step-by-step log: every plan, every action, whether it changed anything, and a link to the visual replay in the app.
open_app	Launches a program on the shared agent desktop and reports its first titled window. The agent desktop starts empty, so this is how anything gets onto it.
read_desktop	Reads the compact element tree of a window on the agent desktop, one line per interactive element, no screenshot. Plan your clicks from this.
click	Clicks one element, chosen by id or name from read_desktop, then verifies against the desktop state and states explicitly whether anything changed.
type_text	Types text into one element on the agent desktop, then verifies whether anything changed.
press_key	Presses a key or key combination such as ctrl+s, enter, tab or alt+f4, optionally focusing an element first, with verification afterwards.
scroll	Scrolls a window or a specific pane and reports whether the content actually moved. A list that is already at the bottom reports no effect.
agent_windows	Lists the windows currently open on the shared agent desktop, frontmost first, so you can pick one by a title substring.

How it works

• The agent works on a second Win32 desktop inside your session. It never takes your foreground, mouse or keyboard, and you can watch it live in the app.
• Tools read the UI Automation element tree instead of screenshots: one line per interactive element, capped at 200 elements per window.
• The click loop of desktop_task runs inside the server on a model endpoint you configure, so its retries and intermediate steps never enter your context.
• Risky actions such as delete, send, pay or install are denied by default on MCP calls and reported, instead of blocking on a confirmation nobody can answer.
• agentfenster sends no telemetry. The only network traffic is the model endpoint you configure for the click loop.

Requirements

Platform	Windows 10 or 11
Transport	stdio, local
Runtime	Python 3.11 or newer, installed with the app
Prerequisite	the agentfenster app (commercial, 3-day trial)

Links

• Product and download: https://agentfenster.com
• MCP documentation: https://agentfenster.com/mcp
• Pricing: https://agentfenster.com/#pricing
• Discord: https://discord.gg/J9MfKP255Y
• Support: hello@agentfenster.com
• Privacy: https://agentfenster.com/privacy
• Terms: https://agentfenster.com/terms

Issues

Use the issue tracker of this repository for bug reports and questions about the MCP server: tool behaviour, install problems, MCP client compatibility. For anything about the app itself, Discord and hello@agentfenster.com are faster.

Rights

agentfenster is commercial closed-source software. No open-source license is granted here. The text in this repository is published so that MCP users and directories can read, quote and link to it. Use of the agentfenster app itself is governed by the terms at https://agentfenster.com/terms.