agent-browser

agent-browser is a skill for Claude Code, Codex from coalesce-labs/catalyst. It costs 101 tokens per session (849 once invoked), scanned A, original, no licence file.

A command-line tool for having an AI agent control a web browser.

In plain words
What is it for?
Use it for browser-based UI testing, screenshots, form filling, and verifying websites.
Why use it?
It provides a way to open sites, complete forms, take screenshots, and check how web pages work during testing.

Skill for Claude CodeCodex

Part of the catalyst-dev plugin — 31 skills, 9 agents shipped together

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/coalesce-labs/catalyst/agent-browser
Any agent
npx skills add coalesce-labs/catalyst --skill agent-browser
Clone the repo
git clone --depth 1 https://github.com/coalesce-labs/catalyst

Made for: Claude Code, Codex.

Or install catalyst-dev, the plugin that ships this one along with the rest of its 31 skills, 9 agents.

Wrote 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.

agentmods badge for agent-browser

README.md
[![agentmods](https://agentmods.dev/badge/skills/coalesce-labs/catalyst/agent-browser.svg)](https://agentmods.dev/skills/coalesce-labs/catalyst/agent-browser)
Your own site
<a href="https://agentmods.dev/skills/coalesce-labs/catalyst/agent-browser"><img src="https://agentmods.dev/badge/skills/coalesce-labs/catalyst/agent-browser.svg" alt="Measured on agentmods" height="20"></a>
Per session 101 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 849 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin unknown 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 $0.00101 $0.00849
Opus 5 $0.00051 $0.00425
Sonnet 5 $0.00020 $0.00170
Haiku 4.5 $0.00010 $0.00085

Measured 5d ago against content hash 85d678e2ceed, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

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 5d 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.

plugins/dev/skills/agent-browser/SKILL.md · 48 lines

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.

Read it on GitHub

Files

What ships with it

3 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. 5d ago First seen · 48 lines · 101 tokens per session scan A 85d678e2ceed

Subscribe to this mod's changes

agent-browser is a skill published in the GitHub repository coalesce-labs/catalyst (20 stars, last pushed 3d ago), with no licence file. It adds 101 tokens to every session and 849 once invoked, about $0.0005 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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