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 agentmods add skills/ynulihao/agentskillos/dev-browsernpx skills add ynulihao/AgentSkillOS --skill dev-browsergit clone --depth 1 https://github.com/ynulihao/AgentSkillOSWhat 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 | $0.00084 | $0.01616 |
| Opus 5 | $0.00042 | $0.00808 |
| Sonnet 5 | $0.00017 | $0.00323 |
| Haiku 4.5 | $0.00008 | $0.00162 |
Grade A, and why
dev-browser 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.
The source is not reproduced here
No licence file
A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.
What ships with it
15 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.
- bun.lock 46 KB
- references/scraping.md 5.2 KB
- scripts/start-relay.ts 677 B runs code
- scripts/start-server.ts 3.6 KB runs code
- server.sh 521 B runs code
- src/client.ts 14 KB runs code
- src/index.ts 8.1 KB runs code
- src/relay.ts 21 KB runs code
- src/snapshot/__tests__/snapshot.test.ts 5.6 KB runs code
- src/snapshot/browser-script.ts 37 KB runs code
- src/snapshot/index.ts 562 B runs code
- src/snapshot/inject.ts 578 B runs code
- src/types.ts 726 B runs code
- tsconfig.json 844 B
- vitest.config.ts 283 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.
- 2d ago First seen · 212 lines · 84 tokens per session scan A 3f04e81004ba
dev-browser is a skill published in the GitHub repository ynulihao/AgentSkillOS (609 stars, last pushed 5mo ago), with no licence file. It adds 84 tokens to every session and 1,616 once invoked, about $0.0004 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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