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arXiv preprint

Magentic-UI: Towards Human-in-the-loop Agentic Systems

Microsoft's open-source agent interface puts the user in the team: co-planning, take-over, action approvals, saved plans. A simulated helper lifted GAIA accuracy from 30.3% to 51.9%.

Breakdown by FDE Interviews · 14 min read · Updated

About the original · 2025
AUTHORS
Mozannar, Bansal, Tan, Fourney, et al.
FROM
Microsoft Research AI Frontiers
PUBLISHED
Jul 2025 · arXiv preprint
CITED BY
60Semantic Scholar · Oct 2026
IN THIS BREAKDOWN · 10 SECTIONS

You can read 17% of this breakdown.

01

The paper in one minute

Magentic-UI is an open-source web application from Microsoft Research for building and studying agents that work with a person rather than for one. Under the interface is a multi-agent team adapted from Magentic-One: an Orchestrator that plans and delegates, a WebSurfer that drives a browser, a Coder that writes and runs Python or Bash, a FileSurfer that reads and converts files, optional agents wrapping MCP servers, and UserProxy, the human, treated as one more agent the Orchestrator can hand work to.

The paper's contribution is six interaction mechanisms meant to keep human effort low.

Co-planning. Before acting, the Orchestrator asks a clarifying question if the task is unclear, then shows a plan as editable steps. Nothing runs until the user accepts.

Co-tasking. The user can pause the agent or take over its browser at any time; the Orchestrator can ask the user for help, but only after other agents have failed.

Action approval. Every action carries a developer-set label (never, maybe or always irreversible). "Always" asks the user; "maybe" goes to an LLM judge.

Answer verification. The user can inspect each step's actions and screenshots or ask follow-up questions.

Memory. A finished run can be turned into a saved plan and reused.

Multitasking. Several sessions run at once, each showing whether it needs input.

The evaluation has four parts: autonomous benchmarks, a simulated-user version of GAIA, a 12-person qualitative study, and 24 adversarial scenarios.

THE IDEA, VISUALLY
PLAN TOGETHER, THEN EXECUTE Co-planning step = (agent, title, details) user edits, regenerates or presses Accept Progress ledger, per round step complete? replan? which agent, what instruction summary of what is known THE TEAM: THE USER IS ONE OF THE AGENTS WebSurfer browser Coder Python, Bash FileSurfer MarkItDown MCP agents optional UserProxy the human The Orchestrator asks the user only after other agents fail, set by one natural-language description field. ACTION GUARD never scroll → run maybe click → LLM judge always upload → ask user Plus: allow-listed websites, a fresh browser with no cookies, and Docker sandboxes for code, files and browsing. Memory = saved (task, plan) pairs, reused or retrieved. GAIA VALIDATION, GPT-4o AGENTS (FIGURE 11) autonomous 30.3 + simulated user, o4-mini 42.6 + simulated user, side info 51.9 The side-info user saw a human-written plan and gave the final answer itself in 18% of tasks. AUTONOMOUS, o4-mini (TABLE 1) Magentic-UI reference GAIA test 42.52 92.00 human AssistantBench 27.6 28.30 best WebVoyager 82.2 89.1 Browser Use WebGames 45.5 95.7 human WebVoyager: WebSurfer only, GPT-4 judge, dates moved to 2025 WEBVOYAGER RUNTIME (FIGURE 9) succeeded median 113.9 s failed median 236.7 s 24 adversarial scenarios: none worked on the default setup; with mitigations off, prompt injection exfiltrated SSH keys.
Magentic-UI plans with the user before acting, treats the user as one more agent the Orchestrator can delegate to, and routes every action through a three-tier guard. The accuracy gains come from simulated users, and the largest one leans on a user who sometimes answered for the agent.
Research notes: the problem, approach and results
30.3% → 51.9%

GAIA validation accuracy, autonomous versus with a simulated user holding a human-written plan; that user gave the final answer in 18% of tasks

10%

of tasks in which the agent asked that simulated user for help, about once each time

0 of 24

adversarial scenarios that succeeded against the default configuration of guards and sandboxes

THE PROBLEM

Agents that browse, run code and handle files are useful but below human accuracy, and their actions can be irreversible or hijacked by a malicious page. Fully autonomous operation asks people to trust a system that is wrong a lot of the time; watching every step defeats the point of delegating.

THE IDEA

Design for low-cost human involvement. Co-plan before acting with an editable list of steps; let the user take over the agent's browser at any time and let the Orchestrator ask the user for help; gate risky actions through a guard; save successful runs as reusable plans; and run several tasks at once with status indicators.

THE RESULT

Autonomously, Magentic-UI matched its predecessor and scored 82.2% on WebVoyager with o4-mini. With a simulated user holding a human-written plan, GAIA validation accuracy rose from 30.3% to 51.9% while the agent asked for help in 10% of tasks. Twelve users found it usable (SUS 74.58); none of 24 attack scenarios succeeded against the default setup.

02

Why it matters to an FDE

Most enterprise agents you deploy will have a human nearby: an analyst approving a payment, a support lead reviewing a draft, an operator who knows that the "right" vendor portal is not the one the agent found. Magentic-UI is a worked design for that arrangement, and several of its choices transfer directly.

Front-load the human's effort. Ten seconds editing a plan before execution is cheaper than correcting a 20-minute run. In the user study, people mostly edited plans to add preferences the agent could not have guessed, such as which website to trust.

Make the human an addressable participant. Modeling the user as an agent with a description ("ask only after others fail") gives one knob for how often the system interrupts.

Classify actions before you judge them. A fixed label per action type handles the easy cases deterministically and sends only ambiguous ones to a model.

Isolate what the agent can reach. The safety results come mostly from sandboxing and a browser with no saved logins. With those mitigations disabled, prompt injection on a web page got the agent to exfiltrate SSH keys and create a GitHub API key.

Read the headline gain with care. The 71% improvement on GAIA comes from a simulated user that had a human-written plan for each task and, in 18% of tasks, supplied the final answer itself. It shows that help is valuable; it does not measure how much a real person's help is worth.

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  • ◇1 architecture diagram
  • </>1 runnable code experiment
  • ▦2 results tables
  • ?5 interview questions with answers
  1. 03Key takeaways

    The mechanisms, the measured results, what the user study found, and three misreadings

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  2. 04How it works

    The planning and execution loop, the agents, the guard, memory retrieval and the deployment layout

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  3. 05The numbers that matter

    Benchmarks, simulated users, runtime, planning statistics, the user study and red-teaming

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  4. 06Try it yourself

    Check the headline arithmetic, then price action approvals and multitasking for one human

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  5. 07Where it breaks

    The simulated-user confound, loose comparisons, small study, guard tuning and paper slips

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  6. 08Using it on a deployment

    Designing human checkpoints for an agent your customer's staff will supervise

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  7. 09Interview angles

    Five questions this paper prepares you for, with answer hints

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