aco

A command-line tool for controlling a live Appium session, which automates apps on iOS and Android devices or simulators.

In plain words
What is it for?
Use it to start sessions, find interface elements, tap, swipe, type, take screenshots, read screen details, and switch to a WebView.
Why use it?
It lets you inspect and operate a running mobile app from shell commands instead of controlling the device manually.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/tai2/aco/aco
Any agent
npx skills add tai2/aco --skill aco
Clone the repo
git clone --depth 1 https://github.com/tai2/aco

Made for: Claude Code, Codex.

Per session 111 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,012 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00111 $0.01012
Opus 5 $0.00056 $0.00506
Sonnet 5 $0.00022 $0.00202
Haiku 4.5 $0.00011 $0.00101

Measured 2d ago against content hash f13d1f1f5c0f, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

aco scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/aco/SKILL.md · 72 lines

How it starts

The opening of the file, as written. The whole thing — 72 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Driving Appium with aco

aco issues one Appium WebDriver command per shell invocation against a live session. Prerequisite: the user has aco (npm i -g @tai2/aco) and appium installed. If aco --help fails, stop and tell the user to install it.

Core loop

  1. Discover a target (only when starting fresh): aco device list (add --platform ios|android, --state all, --json).
  2. Start a session — foreground blocks the shell, so ALWAYS pass --detach so control returns: aco session start --detach --platform ios --app <path-or-bundleId> --device-name "<name>" Android needs --app-activity when --app is an appPackage id, and --avd (or a plugged-in device) to choose the target. session start has no --json flag — it always emits the JSON envelope on stdout. Do not append --json (it errors); for verbatim W3C caps use --caps-json '<json>' instead. Do NOT unzip the build first. Pass the archive straight to --app: the driver extracts it itself. iOS accepts a .zip/.app.zip/.ipa (or an unzipped .app); Android accepts an .apk/.apks. Unzipping a .app.zip to a bare .app is unnecessary and a common mistake.
  3. Inspect before acting — never guess coordinates:
    • aco elements → labelled elements + ready-to-paste tap selectors (use --json to parse).
    • aco screenshot --out shot.png, then Read shot.png to see the screen.
    • aco source (optionally --xpath '<expr>') for the full tree.
  4. Act--session/--server-url/--platform default to the latest live session, so omit them after session start:
    • aco tap --selector 'accessibility id:login.button' (or --label, or --x/--y).
    • aco swipe --direction up (within the default scroll view).
    • aco send-keys --selector '<sel>' --text 'alice' (clears first; --no-clear appends).
    • aco scroll-into-view '<selector>' --direction up.
    • aco element find --using "accessibility id" --value "Login" then aco element click --element <id>.
  5. Verify the effect with another aco screenshot / aco elements.
  6. Stop when done: aco session stop (latest), --all, or --session <id>.

Read the full file on GitHub · 72 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 72 lines · 0 tokens per session scan A f13d1f1f5c0f

Subscribe to this mod's changes

aco is a skill published in the GitHub repository tai2/aco (2 stars, last pushed 2mo ago), licensed MIT. It adds 111 tokens to every session and 1,012 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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