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 attentiondotnet/davidondrej-skills --skill browser-harnessgit clone --depth 1 https://github.com/attentiondotnet/davidondrej-skillsWrote 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/attentiondotnet/davidondrej-skills/browser-harness)<a href="https://agentmods.dev/skills/attentiondotnet/davidondrej-skills/browser-harness"><img src="https://agentmods.dev/badge/skills/attentiondotnet/davidondrej-skills/browser-harness/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/attentiondotnet/davidondrej-skills/browser-harness"><img src="https://agentmods.dev/badge/skills/attentiondotnet/davidondrej-skills/browser-harness.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00038 | $0.02759 |
| Opus 5.5 | $0.00015 | $0.01104 |
| Sonnet 5.5 | $0.00008 | $0.00552 |
| Haiku 4.5 | $0.00004 | $0.00276 |
Grade A, and why
browser-harness 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 2mo 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.
This is a copy
97% identical to browser-harness — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 200 lines — stays where its author put it; the contents beside it link to each section on GitHub.
browser-harness
Direct browser control via CDP. For task-specific edits, use agent-workspace/agent_helpers.py. For setup, install, or connection problems, read install.md.
Routing check first: if the task needs no interaction (no clicks, logins, or forms) and you just want page content, use DeepAPI POST /v1/scrape/website instead of driving a browser — see the deepapi skill. Use browser-harness when the task needs a real browser: interaction, JS-heavy flows, logged-in sessions, or visual verification.
Domain skills (community-contributed per-site playbooks under agent-workspace/domain-skills/) are off by default. Set BH_DOMAIN_SKILLS=1 to enable them; see the bottom section.
If BH_DOMAIN_SKILLS=1 and the task is site-specific, read every file in the matching agent-workspace/domain-skills/<site>/ directory before inventing an approach.
Usage
browser-harness -c '
new_tab("https://docs.browser-use.com")
wait_for_load()
print(page_info())
'
- Invoke as browser-harness — it's on $PATH. No cd, no uv run.
- First navigation is new_tab(url), not goto_url(url) — goto runs in the user's active tab and clobbers their work.
Tool call shape
browser-harness -c '
# any python. helpers pre-imported. daemon auto-starts.
'
run.py calls ensure_daemon() before exec — you never start/stop manually unless you want to.
Remote browsers
Use remote for parallel sub-agents (each gets its own isolated browser via a distinct BU_NAME) or on a headless server. BROWSER_USE_API_KEY must be set. start_remote_daemon, list_cloud_profiles, list_local_profiles, sync_local_profile are pre-imported.
When supervising those sub-agents, after each check send the user one very short status line: what they are doing and whether they are on track.
Claude Code cmux note: after Claude finishes, it may prefill a predicted next user message; that draft is Claude, not the user speaking.
browser-harness -c '
start_remote_daemon("work") # default — clean browser, no profile
# start_remote_daemon("work", profileName="my-work") # reuse a cloud profile (already logged in)
# start_remote_daemon("work", profileId="<uuid>") # same, but by UUID
# start_remote_daemon("work", proxyCountryCode="de", timeout=120) # DE proxy, 2-hour timeout
# start_remote_daemon("work", proxyCountryCode=None) # disable the Browser Use proxy
'
BU_NAME=work browser-harness -c '
new_tab("https://example.com")
print(page_info())
'
What ships with it
1 file 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.
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.
- 2mo ago First seen · 200 lines · 38 tokens per session scan A ab0ed9c1d815
browser-harness is a skill published in the GitHub repository attentiondotnet/davidondrej-skills (11 stars, last pushed 3mo ago), licensed MIT. It adds 38 tokens to every session and 2,759 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 97% identical to browser-harness, differing in 0 lines, and is treated as a copy.
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