Vellum Assistant is a personal AI assistant that remembers information about users, learns their preferences, and takes actions across connected apps. It is intended for people who want an assistant that can manage conversations, unfinished work, and proactive notifications over time. The catalogue skills, hooks, instruction, and setting configure or extend how the assistant works.
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.
npx skills add vellum-ai/vellum-assistant --skill computer-usegit clone --depth 1 https://github.com/vellum-ai/vellum-assistantWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/vellum-ai/vellum-assistant/computer-use)<a href="https://agentmods.dev/skills/vellum-ai/vellum-assistant/computer-use"><img src="https://agentmods.dev/badge/skills/vellum-ai/vellum-assistant/computer-use.svg" alt="Measured on agentmods" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00007 | $0.00463 |
| Opus 5 | $0.00003 | $0.00231 |
| Sonnet 5 | $0.00001 | $0.00093 |
| Haiku 4.5 | $0.00001 | $0.00046 |
Grade A, and why
computer-use 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 yesterday.
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.
What it actually says
This skill provides the computer_use_* action tools for controlling a connected desktop. CU tools run through the main agent loop via HostCuProxy.
The skill is internally preactivated for conversations with a connected desktop client.
Tools in this skill are proxy tools. Execution is forwarded to a connected desktop client and is never handled locally by the assistant.
Window-scoped observation (macOS)
computer_use_observe accepts optional capture_window_id, a native macOS
CGWindowID (not a browser tab ID or accessibility element ID). Obtain the ID
from a current native window inventory before using it; never guess one.
The native helper captures that window and its accessibility tree without
including secondary windows, even when another app covers the selected window.
A missing window must not be replaced with a desktop capture.
This is a single observation, not a session-wide privacy boundary: normal
click/type/scroll and other action tools still return their normal desktop
observations. Do not promise app-only capture for a whole control session.
The desktop must explicitly advertise host_cu_window_capture support on its
connection; the daemon rejects older or unsupported clients before requesting
any capture. Other desktop platforms reject this option.
The screenshot is window-relative, while action coordinates are screen points; do not scale it using full-display dimensions. Prefer accessibility element IDs and ensure the intended window is focused before a later action. Window-scoped observation does not focus the window or confine subsequent input to that app.
What ships with it
12 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.
- TOOLS.json 13 KB
- tools/computer-use-click.ts 714 B runs code
- tools/computer-use-done.ts 386 B runs code
- tools/computer-use-drag.ts 386 B runs code
- tools/computer-use-key.ts 385 B runs code
- tools/computer-use-observe.ts 389 B runs code
- tools/computer-use-open-app.ts 390 B runs code
- tools/computer-use-respond.ts 389 B runs code
- tools/computer-use-run-applescript.ts 414 B runs code
- tools/computer-use-scroll.ts 388 B runs code
- tools/computer-use-type-text.ts 391 B runs code
- tools/computer-use-wait.ts 386 B runs code
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.
- yesterday Changed · +21 lines b2dc092dca6f
- 8d ago First seen · 25 lines · 7 tokens per session scan A 0389441d5383
computer-use is a skill published in the GitHub repository vellum-ai/vellum-assistant (1,204 stars, last pushed today), licensed MIT. It adds 7 tokens to every session and 463 once invoked, about $0.0000 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 2026-08-30.
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Takes any security finding, error message, or jargon-heavy security advice and explains it in plain English. Use this when someone is confused by what /lictor-security-check found, or when they got a security warning from another tool and don't understand it.
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Applies the fixes recommended by /lictor-security-check, with the user's explicit permission for each change. Walks through findings one at a time, shows the proposed change, gets approval, applies, runs tests if available, and moves on. Some fixes (rotating leaked credentials) require the user to act outside Claude …
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