Desktop Computer Automation

CRITICAL RULES — VIOLATIONS WILL BREAK THE WORKFLOW:
Never run midscene commands in the background. Each command must run synchronously so you can read its output (especially screenshots) before deciding the next action. Background execution breaks the screenshot-analyze-act loop.

Run only one midscene command at a time. Wait for the previous command to finish, read the screenshot, then decide the next action. Never chain multiple commands together.
Allow enough time for each command to complete. Midscene commands involve AI inference and screen interaction, which can take longer than typical shell commands. A typical command needs about 1 minute; complex
act
commands may need even longer.
Always report task results before finishing. After completing the automation task, you MUST proactively summarize the results to the user — including key data found, actions completed, screenshots taken, and any relevant findings. Never silently end after the last automation step; the user expects a complete response in a single interaction.

Only minimize windows, never close them unless explicitly asked. When you need to dismiss or get a window out of the way, minimize it instead of closing it. Do not close any app or window unless the user explicitly asks you to do so.

Control your desktop (macOS, Windows, Linux) using

npx -y @midscene/computer@1

. Each CLI command maps directly to an MCP tool — you (the AI agent) act as the brain, deciding which actions to take based on screenshots.

What

act

Can Do

Inside a single

act

call on desktop, Midscene can move the mouse, click, double-click, right-click, drag items, type or clear text, scroll, press single keys or keyboard shortcuts, and work through multi-step interactions on whatever is visible on the selected display.

Prerequisites

Midscene requires models with strong visual grounding capabilities. The following environment variables must be configured — either as system environment variables or in a

.env

file in the current working directory (Midscene loads

.env

automatically):

bash

MIDSCENE_MODEL_API_KEY="your-api-key"
MIDSCENE_MODEL_NAME="model-name"
MIDSCENE_MODEL_BASE_URL="https://..."
MIDSCENE_MODEL_FAMILY="family-identifier"

Example: Gemini (Gemini-3-Flash)

bash

MIDSCENE_MODEL_API_KEY="your-google-api-key"
MIDSCENE_MODEL_NAME="gemini-3-flash"
MIDSCENE_MODEL_BASE_URL="https://generativelanguage.googleapis.com/v1beta/openai/"
MIDSCENE_MODEL_FAMILY="gemini"

Example: Qwen 3.5

bash

MIDSCENE_MODEL_API_KEY="your-aliyun-api-key"
MIDSCENE_MODEL_NAME="qwen3.5-plus"
MIDSCENE_MODEL_BASE_URL="https://dashscope.aliyuncs.com/compatible-mode/v1"
MIDSCENE_MODEL_FAMILY="qwen3.5"
MIDSCENE_MODEL_REASONING_ENABLED="false"
# If using OpenRouter, set:
# MIDSCENE_MODEL_API_KEY="your-openrouter-api-key"
# MIDSCENE_MODEL_NAME="qwen/qwen3.5-plus"
# MIDSCENE_MODEL_BASE_URL="https://openrouter.ai/api/v1"

Example: Doubao Seed 2.0 Lite

bash

MIDSCENE_MODEL_API_KEY="your-doubao-api-key"
MIDSCENE_MODEL_NAME="doubao-seed-2-0-lite"
MIDSCENE_MODEL_BASE_URL="https://ark.cn-beijing.volces.com/api/v3"
MIDSCENE_MODEL_FAMILY="doubao-seed"

Commonly used models: Doubao Seed 2.0 Lite, Qwen 3.5, Zhipu GLM-4.6V, Gemini-3-Pro, Gemini-3-Flash.

If the model is not configured, ask the user to set it up. See Model Configuration for supported providers.

Commands

Connect to Desktop

bash

npx -y @midscene/computer@1 connect
npx -y @midscene/computer@1 connect --displayId <id>

List Displays

bash

npx -y @midscene/computer@1 list_displays

Take Screenshot

bash

npx -y @midscene/computer@1 take_screenshot

After taking a screenshot, read the saved image file to understand the current screen state before deciding the next action.

Perform Action

Use

act

to interact with the computer and get the result. It autonomously handles all UI interactions internally — clicking, typing, scrolling, waiting, and navigating — so you should give it complex, high-level tasks as a whole rather than breaking them into small steps. Describe what you want to do and the desired effect in natural language:

bash

# specific instructions
npx -y @midscene/computer@1 act --prompt "type hello world in the search field and press Enter"
npx -y @midscene/computer@1 act --prompt "drag the file icon to the Trash"

# or target-driven instructions
npx -y @midscene/computer@1 act --prompt "search for the weather in Shanghai using the Chrome browser, tell me the result"

Assert Current Screen State

Use

assert

to verify that the current screen satisfies a natural language condition. It does not perform UI actions; it checks the visible screen state and passes only when the assertion is true. Use this for validation, QA checks, and final state verification after

act

bash

npx -y @midscene/computer@1 assert --prompt "there is a login button visible"
npx -y @midscene/computer@1 assert --prompt "the active window shows a saved confirmation message"
npx -y @midscene/computer@1 assert --displayId 1 --prompt "the file picker is open"

Use a Reference Image for Precise Targeting

When the user provides a screenshot, icon, logo, or reference image and wants an exact visual match, prefer

tap --locate

instead of a generic

act --prompt

. Pass

--locate

as JSON. The

prompt

describes the target,

images

supplies named reference images, and

convertHttpImage2Base64: true

is useful when the image URL may not be directly accessible to the model.

bash

npx -y @midscene/computer@1 tap --locate '{
  "prompt": "tap the area contains the image",
  "images": [
    {
      "name": "target image",
      "url": "https://github.githubassets.com/assets/GitHub-Mark-ea2971cee799.png"
    }
  ],
  "convertHttpImage2Base64": true
}'

The same

locate

JSON shape also works for other commands that accept a

locate

parameter.

Disconnect

bash

npx -y @midscene/computer@1 disconnect

Consume Report Files

The generated HTML report is recommended for human reading first. It includes step-by-step execution details and replay videos for each operation, which makes it much easier to understand what happened and troubleshoot problems.

If another skill or tool needs to consume the report, first convert it with

report-tool

from the same platform CLI package. Prefer Markdown for LLM-based workflows. Use JSON when the report needs to be processed programmatically.

bash

npx -y @midscene/computer@1 report-tool --action to-markdown --htmlPath ./midscene_run/report/.../index.html --outputDir ./output-markdown
npx -y @midscene/computer@1 report-tool --action split --htmlPath ./midscene_run/report/.../index.html --outputDir ./output-data

Workflow Pattern

Since CLI commands are stateless between invocations, follow this pattern:

Connect to establish a session
Health check — observe the output of the
```
connect
```
command. If
```
connect
```
already performed a health check (screenshot and mouse movement test), no additional check is needed. If
```
connect
```
did not perform a health check, do one manually: take a screenshot and verify it succeeds, then move the mouse to a random position (
```
act --prompt "move the mouse to a random position"
```
) and verify it succeeds. If either step fails, stop and troubleshoot before continuing. Only proceed to the next steps after both checks pass without errors.
Launch the target app and take screenshot to see the current state, make sure the app is launched and visible on the screen.
Execute action using
```
act
```
to perform the desired action or target-driven instructions, and use
```
assert
```
when you need to verify the resulting screen state.
Disconnect when done
Report results — summarize what was accomplished, present key findings and data extracted during the task, and list any generated files (screenshots, logs, etc.) with their paths

Best Practices

Always run a health check first: After connecting, observe the output of the
```
connect
```
command. If
```
connect
```
already performed a health check (screenshot and mouse movement test), no additional check is needed. If it did not, do one manually: take a screenshot and move the mouse to a random position. Both must succeed (no errors) before proceeding with any further operations. This catches environment issues early.
Bring the target app to the foreground before using this skill: For best efficiency, bring the app to the foreground using other means (e.g.,
```
open -a <AppName>
```
on macOS,
```
start <AppName>
```
on Windows) before invoking any midscene commands. Then take a screenshot to confirm the app is actually in the foreground. Only after visual confirmation should you proceed with UI automation using this skill. Avoid using Spotlight, Start menu search, or other launcher-based approaches through midscene — they involve transient UI, multiple AI inference steps, and are significantly slower.
Be specific about UI elements: Instead of vague descriptions, provide clear, specific details. Say
```
"the yellow minimize button in the top-left corner of the Safari window"
```
instead of
```
"the button"
```
.
Describe locations when possible: Help target elements by describing their position (e.g.,
```
"the icon in the top-right corner of the menu bar"
```
,
```
"the third item in the left sidebar"
```
).
Never run in background: Every midscene command must run synchronously — background execution breaks the screenshot-analyze-act loop.
Check for multiple displays: If you launched an app but cannot see it on the screenshot, the app window may have opened on a different display. Use
```
list_displays
```
to check available displays. You have two options: either move the app window to the current display, or use
```
connect --displayId <id>
```
to switch to the display where the app is.
Batch related operations into a single
act
command: When performing consecutive operations within the same app, combine them into one
```
act
```
prompt instead of splitting them into separate commands. For example, "search for X, click the first result, and scroll down to see more details" should be a single
```
act
```
call, not three. This reduces round-trips, avoids unnecessary screenshot-analyze cycles, and is significantly faster.
Set up
PATH
before running (macOS): On macOS, some commands (e.g.,
```
system_profiler
```
) may not be found if the
```
PATH
```
is incomplete. Before running any midscene commands, ensure the
```
PATH
```
includes the standard system directories:
bash
```
export PATH="/usr/sbin:/usr/bin:/bin:/sbin:$PATH"
```
This prevents screenshot failures caused by missing system utilities.
Use
assert
for verification: When the goal is to confirm that a screen state is true, use
```
assert --prompt "..."
```
instead of an
```
act
```
prompt. Keep assertions observable and specific, such as
```
"the Save dialog is open"
```
or
```
"the export completed message is visible"
```
.
Always report results after completion: After finishing the automation task, you MUST proactively present the results to the user without waiting for them to ask. This includes: (1) the answer to the user's original question or the outcome of the requested task, (2) key data extracted or observed during execution, (3) screenshots and other generated files with their paths, (4) a brief summary of steps taken. Do NOT silently finish after the last automation command — the user expects complete results in a single interaction.
Prefer
tap --locate
when a reference image is provided: If the user shares a screenshot, icon, or logo and wants that exact visual target, use
```
tap --locate
```
with a multimodal
```
locate
```
JSON object such as
```
{ "prompt": "...", "images": [...] }
```
instead of relying only on
```
act --prompt
```
.

Example — Context menu interaction:

bash

npx -y @midscene/computer@1 act --prompt "right-click the file icon and select Delete from the context menu"
npx -y @midscene/computer@1 take_screenshot

Example — Dropdown menu:

bash

npx -y @midscene/computer@1 act --prompt "open the File menu and click New Window"
npx -y @midscene/computer@1 take_screenshot

Troubleshooting

macOS: Accessibility Permission Denied

Your terminal app does not have Accessibility access:

Open System Settings > Privacy & Security > Accessibility
Add your terminal app and enable it
Restart your terminal app after granting permission

macOS: Xcode Command Line Tools Not Found

bash

xcode-select --install

API Key Not Set

Check

.env

file contains

MIDSCENE_MODEL_API_KEY=<your-key>

macOS: Screenshot Fails with

system_profiler

Not Found

take_screenshot

fails with an error like

system_profiler: command not found

, the

PATH

environment variable is likely incomplete. Fix it by running:

bash

export PATH="/usr/sbin:/usr/bin:/bin:/sbin:$PATH"

Then retry the screenshot command.

macOS: Screenshot Returns a Black Screen

take_screenshot

returns a completely black image, the Mac is likely locked (e.g. screen is at the login/lock window). This is a system-level restriction — macOS prohibits capturing the screen contents while the session is locked, so there is no workaround at the application level.

Recommended fix: Use a screensaver instead of locking the screen. A screensaver keeps the user session active and unlocked, allowing screenshots to capture normally.

Open System Settings > Lock Screen
Set "Require password after screen saver begins or display is turned off" to a longer delay (or turn it off during automation)
Optionally configure a screensaver under System Settings > Screen Saver so the display still dims after inactivity without locking

AI Cannot Find the Element

Take a screenshot to verify the element is actually visible
Use more specific descriptions (include color, position, surrounding text)
Ensure the element is not hidden behind another window

@midscene/*

Dependency Version Outdated

Check local versions:

npm ls @midscene/computer @midscene/core @midscene/shared

(or

pnpm why @midscene/computer

Check latest versions:

npm view @midscene/computer version

npm view @midscene/core version

npm view @midscene/shared version

Upgrade dependencies:

npm i @midscene/computer@latest @midscene/core@latest @midscene/shared@latest

computer-automation

NPX Install

Tags

SKILL.md Content

Desktop Computer Automation

What
`act`
Can Do

Prerequisites

Commands

Connect to Desktop

List Displays

Take Screenshot

Perform Action

Assert Current Screen State

Use a Reference Image for Precise Targeting

Disconnect

Consume Report Files

Workflow Pattern

Best Practices

Troubleshooting

macOS: Accessibility Permission Denied

macOS: Xcode Command Line Tools Not Found

API Key Not Set

macOS: Screenshot Fails with
`system_profiler`
Not Found

macOS: Screenshot Returns a Black Screen

AI Cannot Find the Element

`@midscene/*`
Dependency Version Outdated