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 antithesishq/antithesis-skills --skill antithesis-agent-browsergit clone --depth 1 https://github.com/antithesishq/antithesis-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/antithesishq/antithesis-skills/antithesis-agent-browser)<a href="https://agentmods.dev/skills/antithesishq/antithesis-skills/antithesis-agent-browser"><img src="https://agentmods.dev/badge/skills/antithesishq/antithesis-skills/antithesis-agent-browser/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/antithesishq/antithesis-skills/antithesis-agent-browser"><img src="https://agentmods.dev/badge/skills/antithesishq/antithesis-skills/antithesis-agent-browser.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00068 | $0.01862 |
| Opus 5 | $0.00034 | $0.00931 |
| Sonnet 5 | $0.00014 | $0.00372 |
| Haiku 4.5 | $0.00007 | $0.00186 |
Grade A, and why
antithesis-agent-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.
How it starts
The opening of the file, as written. The whole thing — 164 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Antithesis agent-browser
Skill version: 2026-09-08 2e4a837
A helper skill for reading data from authenticated Antithesis web pages
when the snouty API doesn't expose what's needed. Other skills
(antithesis-triage, antithesis-debug, antithesis-query-logs) delegate
here when they need an authenticated browser session.
Purpose
- Handle interactive authentication to the user's Antithesis tenant with minimal disruption.
- Load Antithesis web pages (reports, logs, runs, causality) and extract data from them via an injected runtime.
When to use
- When another skill needs information from an Antithesis page that snouty cannot reliably provide.
- When the user or another skill needs to interact with an Antithesis web page directly.
Prerequisites
- DO NOT PROCEED if
agent-browseris not installed. Seehttps://raw.githubusercontent.com/vercel-labs/agent-browser/refs/heads/main/README.mdfor installation options. - DO NOT PROCEED if
agent-browseris older than versionv0.23.4. You can upgrade withagent-browser upgrade. - DO NOT PROCEED if
jqis not installed. Seehttps://jqlang.org/download/for installation options.
Reference files: This skill's references/ directory contains detailed guides for specific tasks. Do NOT read them all up front — only read a reference file when you are told to. Each reference file is mentioned by name at the point where it is needed.
General guidance
- Always ensure you are authenticated first.
- Use disposable sessions. Generate a unique
SESSIONfor each invocation of this skill. - Inject the runtime after navigation. After every
open, after link clicks that may change pages, and after reopening a report from a finding route, wait untilnetworkidle, injectassets/antithesis-agent-browser.js, then use the matching*.waitForReady()method before continuing. - Never run
agent-browsercalls in parallel. They are stateful with side effects. - Retry missing-runtime errors by reinjecting. If a command fails because
window.__antithesisAgentBrowseris undefined or missing, inject the runtime and rerun the same method. - Keep report evals on the main report view. If you click into another page by accident, reopen the original report URL before using report queries again.
What ships with it
6 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.
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 Changed cc2e557768cb
- 7d ago Changed 41f581b54f43
- 11d ago First seen · 164 lines · 68 tokens per session scan A 6936921ac7f2
antithesis-agent-browser is a skill published in the GitHub repository antithesishq/antithesis-skills (267 stars, last pushed 2d ago), licensed Apache-2.0. It adds 68 tokens to every session and 1,862 once invoked, about $0.0003 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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