• Features
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• Computer Use

Computer Use

Hermes Agent can drive your desktop — clicking, typing, scrolling, dragging — in thebackgroundonmacOS, Windows, and Linux. Your cursor doesn’t move, keyboard focus doesn’t change, and your virtual desktops / Spaces don’t switch on you. You and the agent co-work on the same machine.

Unlike most computer-use integrations, this works withany tool-capable model— Claude, GPT, Gemini, or an open model on a local OpenAI-compatible endpoint. There’s no Anthropic-native schema to worry about.

How it works​

Thecomputer_usetoolset speaks MCP over stdio tocua-driver, an open-source background computer-use driver. Each platform uses the appropriate accessibility + input stack under the hood:

computer_use cua-driver | Platform | Accessibility tree | Input dispatch | | — | — | — | | macOS | AX (private SkyLight SPIs) | SLPSPostEventRecordTo— pid-scoped, no cursor warp | | Windows | UIAutomation | SendInput+PostMessage— no focus steal | | Linux | AT-SPI (X11 + Wayland) | XTest (X11) / virtual-keyboard (Wayland) |

SLPSPostEventRecordTo SendInput PostMessage

The result is the same on every platform: the agent can read the accessibility tree of any visible window AND post synthesized events without bringing it to front, switching virtual desktops, or moving the real OS cursor.

For the underlying contract —whybackground mode matters, the no-foreground invariant, click-dispatch internals — seecua.ai/docs/explanation/the-no-foreground-contract.

Enabling​

Pick whichever path is most convenient — both run the same upstream installer:

Option 1: dedicated CLI command (most direct).

hermes computer-use install

This fetches and runs the upstream cua-driver installer —install.shon macOS/Linux,install.ps1on Windows. Usehermes computer-use statusto verify the install.

install.sh install.ps1 hermes computer-use status

Option 2: enable the toolset interactively.

1. Runhermes tools, pick🖱️ Computer Use (macOS/Windows/Linux).
2. The setup runs the upstream installer (same as Option 1).

hermes tools 🖱️ Computer Use (macOS/Windows/Linux)

After installing, regardless of which path you took, grant the platform-appropriate prereqs:

hermes computer-use doctor DISPLAY XDG_SESSION_TYPE=wayland

Then start a session with the toolset enabled:

hermes -t computer_use chat

or addcomputer_useto your enabled toolsets in~/.hermes/config.yaml.

computer_use ~/.hermes/config.yaml

hermes computer-use doctor— your first triage stop​

hermes computer-use doctor

hermes computer-use doctorruns cua-driver’s structuredhealth_reportMCP tool and prints a per-check matrix. It’s the single fastest way to find outwhyan action isn’t working.

hermes computer-use doctor health_report

$ hermes computer-use doctor⚠️  cua-driver 0.5.8 on darwin — degraded  ✅ binary_version: cua-driver 0.5.8  ✅ platform_supported: macOS 26.4.1 (arm64)  ✅ session_active: MCP session is active.  ❌ bundle_identity: Process has no CFBundleIdentifier.      → Run the binary inside CuaDriver.app so TCC grants attribute correctly.  ✅ tcc_accessibility: Accessibility is granted.  ✅ tcc_screen_recording: Screen Recording is granted.  ✅ ax_capability: AX is trusted and reachable.  ✅ screen_capture_capability: ScreenCaptureKit reachable; 1 display(s) shareable.

• Exit code 0when overall isok— everything’s wired up.
• Exit code 1whendegradedorfailed— at least one check failed; the hint on each failure tells you what to fix.
• Exit code 2when the cua-driver binary itself isn’t reachable.

ok degraded failed

Useful flags:

• –include CHECK— run only the listed checks (repeat for multiple)
• –skip CHECK— skip a check (wins over–include)
• –json— emit the raw structured payload, same shape as thetools/call health_reportMCP response

--include CHECK --skip CHECK --include --json tools/call health_report

The check matrix is platform-aware:bundle_identity/tcc_*areskipon Windows + Linux because those concepts don’t apply.ax_capabilitychecks AX on macOS, UIA on Windows, AT-SPI on Linux — each with the right diagnostic hint when it can’t reach.

bundle_identity tcc_* skip ax_capability

The agent cursor and sessions​

When the agent acts, you’ll see atinted overlay cursorglide across the screen to where each click / type / scroll lands. The real OS cursor never moves — the overlay is a visual cue that says “the agent is acting here.” Each Hermes run declares its own cua-driversession id(something likehermes-3a7b9c14d2e8); the cursor’s identity is keyed to that session, so concurrent runs / subagents each get their own cursor without stepping on each other.

hermes-3a7b9c14d2e8

Tune the cursor withcua-driver’s CLI flags or the runtimeset_agent_cursor_styleMCP tool — seecua.ai/docs/how-to-guides/driver/personalize-cursorfor the full menu (built-inarrowvsteardropsilhouette, custom SVG / PNG / ICO via–cursor-icon, runtime gradient colors, bloom halo).

cua-driver set_agent_cursor_style arrow teardrop --cursor-icon

Going deeper — the cua-driver skill pack​

Hermes intentionally keeps its skill (skills/computer-use/SKILL.md) focused on the Hermes-sidecomputer_useaction vocabulary — the single source of truth the agent loads. For the deeper material — platform-specific deep dives, recording semantics, browser page interaction — point your agent harness at the cua-driver skill pack the cua-driver team ships and maintains directly:

skills/computer-use/SKILL.md computer_use

cua-driver skills install

This symlinks the pack into your agent harness’ skill directory. After running it, an agent gets access to:

SKILL.md MACOS.md WINDOWS.md ApplicationFrameHost LINUX.md RECORDING.md WEB_APPS.md TESTS.md

These areplatform deep dives, not duplicates of the Hermes skill— when an agent reports “on Windows, my click landed on the wrong element,” it readsWINDOWS.mdfor the UIA / UWP context that explains why and what to do differently.

WINDOWS.md

cua-driver skills statusshows what’s installed and which agent harnesses it’s linked into. Today the autodetect list covers Claude Code, Codex, OpenCode, OpenClaw, and Antigravity;Hermes autodetection is planned as a follow-up intrycua/cua— until then, runcua-driver skills installonce and point your harness at the resulting~/.cua-driver/skills/cua-driverdirectory (or symlink it into your usual skill space).

cua-driver skills status trycua/cua cua-driver skills install ~/.cua-driver/skills/cua-driver

Quick example​

User prompt:”Find my latest email from Stripe and summarise what they want me to do.”

The agent’s plan (this is the same shape on macOS / Windows / Linux — the model substitutes the platform’s idiomatic shortcut and app name):

1. computer_use(action=”capture”, mode=”som”, app=”Mail”)— gets a screenshot of the email app with every sidebar item, toolbar button, and message row numbered.
2. computer_use(action=”click”, element=14)— clicks the search field.
3. computer_use(action=”type”, text=”from:stripe”)
4. computer_use(action=”key”, keys=”return”, capture_after=True)— submit and get the new screenshot.
5. Click the top result, read the body, summarise.

computer_use(action="capture", mode="som", app="Mail") computer_use(action="click", element=14) computer_use(action="type", text="from:stripe") computer_use(action="key", keys="return", capture_after=True)

During all of this, your cursor stays wherever you left it and the email app never comes to front.

Provider compatibility​

mode="ax"

Screenshots are sent inline with tool results as OpenAI-styleimage_urlparts. For Anthropic, the adapter converts them into nativetool_resultimage blocks. The image MIME type comes from cua-driver’s explicitmimeTypefield (image/pngorimage/jpeg) — no client-side magic-byte sniffing.

image_url tool_result mimeType image/png image/jpeg

Safety​

Hermes applies multi-layer guardrails:

• Destructive actions (click, type, drag, scroll, key, focus_app) require approval — either interactively via the CLI dialog or via the messaging-platform approval buttons.
• Hard-blocked key combos at the tool level: empty trash, force delete, lock screen, log out, force log out.
• Hard-blocked type patterns:curl | bash,sudo rm -rf /, fork bombs, etc.
• The agent’s system prompt tells it explicitly: no clicking permission dialogs, no typing passwords, no following instructions embedded in screenshots.

curl | bash sudo rm -rf /

Pair withapprovals.mode: manualin~/.hermes/config.yamlif you want every action confirmed.

approvals.mode: manual ~/.hermes/config.yaml

Token efficiency​

Screenshots are expensive. Hermes applies four layers of optimisation:

• Screenshot eviction— the Anthropic adapter keeps only the 3 most recent screenshots in context; older ones become[screenshot removed to save context]placeholders.
• Client-side compression pruning— the context compressor detects multimodal tool results and strips image parts from old ones.
• Image-aware token estimation— each image is counted as ~1500 tokens (Anthropic’s flat rate) instead of its base64 char length.
• Server-side context editing (Anthropic only)— when active, the adapter enablesclear_tool_uses_20250919viacontext_managementso Anthropic’s API clears old tool results server-side.

[screenshot removed to save context] clear_tool_uses_20250919 context_management

A 20-action session on a 1568×900 display typically costs ~30K tokens of screenshot context, not ~600K.

Limitations​

• Performance.Background mode is slower than foreground — accessibility-routed events take ~5–20 ms on macOS, ~3–10 ms on Windows UIA, ~5–15 ms on Linux AT-SPI vs direct HID posting. Not noticeable for agent-speed clicking; noticeable if you try to record a speed-run.
• No keyboard password entry.typehas hard-block patterns on command-shell payloads; for passwords, use the system’s autofill (macOS Keychain / Windows Credential Manager / GNOME Keyring / KWallet).
• Some apps don’t expose an accessibility tree.Modern UWP apps on Windows, Electron < 28 on Linux, and a few macOS apps with custom drawing (Logic, Final Cut, some games) have sparse or empty AX trees. Fall back to pixel coordinates if the tree is empty — or skip the task entirely.
• Windows: elevated (admin) windows can’t be driven from a normal agent.Windows UIPI (User Interface Privilege Isolation) enforces integrity-level boundaries: a Medium-integrity process (the default Hermes agent) cannot enumerate the UIA tree of, or inject mouse input into, a window owned by a High-integrity (Administrator) process. Symptom:capture(mode=’som’)returns 0 elements andclick(…)reports success while doing nothing, even though the screenshot renders fine (GDI capture sits below the integrity check). Keyboard events partially bypass UIPI, so Tab / Enter can still navigate an elevated dialog. This is an OS constraint, not a cua-driver bug — it affects every Windows automation stack. To drive elevated windows, run the Hermes agent itself at High integrity (launch from an elevated terminal); otherwise target non-elevated windows.
• Platform-specific deployment gotchas:macOSuses private SkyLight SPIs. Apple can change them in any OS update. Hermes warns when the installed cua-driver is older than the version it was tested against.WindowsSSH sessions run inSession 0, which has no interactive desktop. Drive Hermes from inside the RDP / console session, or set up cua-driver’s autostart Scheduled Task —windows-sshhas the recipe.Linuxrequires a reachable display server. Headless servers need Xvfb (Xvfb :99 -screen 0 1920x1080x24) beforecomputer_usecan capture or inject events. Pure Wayland sessions need an XWayland bridge for screen capture (cua-driver’s Wayland inject path handles input independently).

type capture(mode='som') click(...)

• macOSuses private SkyLight SPIs. Apple can change them in any OS update. Hermes warns when the installed cua-driver is older than the version it was tested against.
• WindowsSSH sessions run inSession 0, which has no interactive desktop. Drive Hermes from inside the RDP / console session, or set up cua-driver’s autostart Scheduled Task —windows-sshhas the recipe.
• Linuxrequires a reachable display server. Headless servers need Xvfb (Xvfb :99 -screen 0 1920x1080x24) beforecomputer_usecan capture or inject events. Pure Wayland sessions need an XWayland bridge for screen capture (cua-driver’s Wayland inject path handles input independently).

Xvfb :99 -screen 0 1920x1080x24 computer_use

For cross-platform GUI automation without the desktop overhead (and without TCC / Session 0 / X11 setup), thebrowsertoolset uses a real headless Chromium and is the right answer for web-only tasks.

browser

Configuration​

Override the driver binary path (tests / CI / local builds):

HERMES_CUA_DRIVER_CMD=/path/to/your/cua-driver

Swap the backend entirely (for testing):

HERMES_COMPUTER_USE_BACKEND=noop   # records calls, no side effects

Telemetry​

cua-driver ships with anonymous usage telemetry (PostHog) enabled by default upstream.Hermes disables it for you— on every cua-driver invocation (the MCP backend,status,doctor, and install) Hermes setsCUA_DRIVER_RS_TELEMETRY_ENABLED=0in the driver’s environment.

status doctor CUA_DRIVER_RS_TELEMETRY_ENABLED=0

To opt back in (let cua-driver use its own default and send telemetry), set this inconfig.yaml:

config.yaml

computer_use:  cua_telemetry: true   # default: false (telemetry off)

When it’s on,hermes computer-use doctorreportstelemetry: enabled; when off (the default), it reportstelemetry: disabled via CUA_DRIVER_RS_TELEMETRY_ENABLED.

hermes computer-use doctor telemetry: enabled telemetry: disabled via CUA_DRIVER_RS_TELEMETRY_ENABLED

Testing against a local cua-driver build​

When you’re developing cua-driver itself — or want to test an unreleased fix — point Hermes at a binary you built from source instead of the published release. Hermes resolves the driver withshutil.which(“cua-driver”)anddoes not enforceHERMES_CUA_DRIVER_VERSION, so a local build (reported as0.0.0-local-*) is accepted as-is. Two approaches:

shutil.which("cua-driver") HERMES_CUA_DRIVER_VERSION 0.0.0-local-*

Option A —install-local(build + put it on PATH)​

install-local

From yourtrycua/cuacheckout, run the upstream local installer. It builds the Rust backend in release mode and dropscua-driverinto the same install layout the production installer uses, adding its bin dir to your PATH:

trycua/cua cua-driver

# Windows (PowerShell), from the cua repo root./libs/cua-driver/scripts/install-local.ps1 -NoAutoStart

# macOS / Linux, from the cua repo root  (defaults to a debug build without --release)./libs/cua-driver/scripts/install-local.sh --release

• Windows stages the build under%USERPROFILE%.cua-driver\packages\…and junctions%LOCALAPPDATA%\Programs\Cua\cua-driver\bin(added to your User PATH) to it. macOS/Linux symlinkscua-driverinto~/.local/bin(override with–bin-dir ).
• -NoAutoStartskips registering thecua-driver-servelogon daemon — you don’t need it for Hermes testing (see notes).

%USERPROFILE%\.cua-driver\packages\… %LOCALAPPDATA%\Programs\Cua\cua-driver\bin cua-driver ~/.local/bin --bin-dir <path> -NoAutoStart cua-driver-serve

Then open a fresh shell (so the PATH change is visible) and confirm:

cua-driver --version                 # local builds report 0.0.0-local-release# Windows:      (Get-Command cua-driver).Source# macOS/Linux:  which cua-driver

Option B — point Hermes straight at the built binary (fastest loop)​

Skip the install ceremony entirely:cargo buildand setHERMES_CUA_DRIVER_CMDto the resulting binary. Best for rapid edit/build/test.

cargo build HERMES_CUA_DRIVER_CMD

cargo build -p cua-driver            # add --release for a release build; run from libs/cua-driver/rust

# Windows (.env)HERMES_CUA_DRIVER_CMD=C:\path\to\cua\libs\cua-driver\rust\target\debug\cua-driver.exe# macOS / Linux (.env)HERMES_CUA_DRIVER_CMD=/path/to/cua/libs/cua-driver/rust/target/debug/cua-driver

Confirm Hermes is using your build​

• hermes computer-use statusprints the resolved binary path and version.
• hermes computer-use doctorconfirms the binary is reachable and exercises the full MCP path end-to-end.
• In a session,computer_use(action=”capture”)exercises the spawnedcua-driver mcpchild process.

hermes computer-use status hermes computer-use doctor computer_use(action="capture") cua-driver mcp

Notes & gotchas​

• Hermes spawns its owncua-driver mcpchild over stdio— it doesnotattach to the long-runningcua-driver serveautostart daemon or its named pipe. So the scheduled task / LaunchAgent is unnecessary for testing (-NoAutoStartis fine). The autostart daemon and the Windows UIAccess worker (cua-driver-uia.exe) only matter for foreground-safe input on some apps (e.g. WPF); the standard tool surface works through the stdio child. On Windows SSH sessions, the autostart pattern IS needed — see the Limitations section.
• Locked binary on Windows.A runningcua-driver-servedaemon can holdcua-driver.exeand block an overwrite on rebuild.install-local.ps1renames the locked binary out of the way automatically; if youcargo buildmanually (Option B), stop it first withcua-driver autostart disable(orschtasks /End /TN cua-driver-serve).
• Rebuild loop.After editing cua-driver source, re-runinstall-local(rebuilds, restages, flips thecurrentjunction) for Option A, or just re-cargo buildfor Option B — no Hermes change needed either way.
• Local builds skip the version check.Hermes warns when the installed cua-driver is older than its per-OS tested baseline, but exempts0.0.0-local-*dev builds — so your local build never triggers that warning.

cua-driver mcp cua-driver serve -NoAutoStart cua-driver-uia.exe cua-driver-serve cua-driver.exe install-local.ps1 cargo build cua-driver autostart disable schtasks /End /TN cua-driver-serve install-local current cargo build 0.0.0-local-*

Troubleshooting​

First action when anything’s off: runhermes computer-use doctor.The structured per-check matrix tells you (and any agent helping you debug) exactly what’s wrong.

hermes computer-use doctor

Specific failure modes the doctor doesn’t catch:

computer_use backend unavailable: cua-driver is not installed— Runhermes computer-use installto fetch the cua-driver binary, or runhermes toolsand enable the Computer Use toolset.

computer_use backend unavailable: cua-driver is not installed hermes computer-use install hermes tools

Clicks seem to have no effect— Capture and verify. A modal you didn’t see may be blocking input. Dismiss it withescapeor the close button.

escape

Element indices are stale— SOM indices are only valid until the nextcapture. Re-capture after any state-changing action. The wrapper carries opaqueelement_tokens for stale detection — you’ll see an explicit error rather than a wrong click.

capture element_token

“blocked pattern in type text”— The text you tried totypematches the dangerous-shell-pattern list. Break the command up or reconsider.

type

Empty captures on Linux—DISPLAYnot set, or you’re on pure Wayland without an XWayland bridge.hermes computer-use doctorwill flag this asax_capability: failwith aSet DISPLAY (X11)…hint.

DISPLAY hermes computer-use doctor ax_capability: fail Set DISPLAY (X11)…

Empty captures on Windows over SSH— You’re in Session 0 (the services session). Drive from RDP / console directly, or set up the autostart pattern — seecua.ai/docs/how-to-guides/driver/windows-ssh.

See also​

• Hermes-side skill—skills/computer-use/SKILL.md— teaches the Hermescomputer_useaction vocabulary; this is what the agent loads.
• cua-driver skill pack— for platform-specific deep dives (macOS no-foreground contract, Windows UIA + Session 0, Linux AT-SPIX11/Wayland, recording, browser pages), runcua-driver skills installand readMACOS.md/WINDOWS.md/LINUX.md/RECORDING.md/WEB_APPS.md. Oncecua-driver skills installautodetects Hermes (planned follow-up), this happens automatically on install.
• cua.ai/docs— the cua-driver project’s documentation:What is computer use?— concept introThe no-foreground contract—whybackground mode mattersInstall reference— cross-platform install detailsPersonalize the agent cursor— built-in shapes, custom assets, runtime overridesDrive Windows over SSH— the Session 0 → Session 1+ autostart patternKeep cua-driver running— autostart / daemon lifecycleConnect your agent— register cua-driver with various harnesses (Hermes among them)
• cua-driver source (trycua/cua)
• Browser automationfor cross-platform web tasks where you don’t need to drive native apps.

skills/computer-use/SKILL.md computer_use

• X11/Wayland, recording, browser pages), runcua-driver skills installand readMACOS.md/WINDOWS.md/LINUX.md/RECORDING.md/WEB_APPS.md. Oncecua-driver skills installautodetects Hermes (planned follow-up), this happens automatically on install.

cua-driver skills install MACOS.md WINDOWS.md LINUX.md RECORDING.md WEB_APPS.md cua-driver skills install

• What is computer use?— concept intro
• The no-foreground contract—whybackground mode matters
• Install reference— cross-platform install details
• Personalize the agent cursor— built-in shapes, custom assets, runtime overrides
• Drive Windows over SSH— the Session 0 → Session 1+ autostart pattern
• Keep cua-driver running— autostart / daemon lifecycle
• Connect your agent— register cua-driver with various harnesses (Hermes among them)