agent-browser

agent-browser is a skill for Claude Code, Codex from Chachamaru127/claude-code-harness. It costs 53 tokens per session (1,592 once invoked), scanned A, original, MIT.

A command-line tool for controlling a web browser through an automated coding agent. It can open pages, inspect interactive elements, fill forms, click controls, take screenshots, and collect page content.

In plain words
What is it for?
Use it to navigate websites, submit forms, inspect page state, take screenshots, scrape information, and investigate user-interface problems.
Why use it?
It avoids having to perform browser checks manually and gives the agent a repeatable way to test web pages and web apps.

Skill for Claude CodeCodex

Part of the claude-code-harness plugin — 25 skills, 5 commands, 5 agents, 27 hooks 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/chachamaru127/claude-code-harness/agent-browser
Any agent
npx skills add Chachamaru127/claude-code-harness --skill agent-browser
Clone the repo
git clone --depth 1 https://github.com/Chachamaru127/claude-code-harness

Made for: Claude Code, Codex.

Or install claude-code-harness, the plugin that ships this one along with the rest of its 25 skills, 5 commands, 5 agents, 27 hooks.

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/chachamaru127/claude-code-harness/agent-browser.svg)](https://agentmods.dev/skills/chachamaru127/claude-code-harness/agent-browser)
Your own site
<a href="https://agentmods.dev/skills/chachamaru127/claude-code-harness/agent-browser"><img src="https://agentmods.dev/badge/skills/chachamaru127/claude-code-harness/agent-browser.svg" alt="Measured on agentmods" height="20"></a>
Per session 53 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,592 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original 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 $0.00053 $0.01592
Opus 5 $0.00026 $0.00796
Sonnet 5 $0.00011 $0.00318
Haiku 4.5 $0.00005 $0.00159

Measured 4d ago against content hash 3414853814ba, 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 4d 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.

codex/.codex/skills/agent-browser/SKILL.md · 188 lines

How it starts

The opening of the file, as written. The whole thing — 188 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent Browser Skill

ブラウザ自動化を行うスキル。agent-browser CLI を使用して、UI デバッグ・検証・自動操作を実行します。


トリガーフレーズ

このスキルは以下のフレーズで自動起動します:

  • 「ページを開いて」「URLを確認して」
  • 「クリックして」「入力して」「フォームに」
  • 「スクリーンショットを撮って」
  • 「UIを確認して」「画面をテストして」
  • "open this page", "click on", "fill the form", "screenshot"

機能詳細

機能 詳細
ブラウザ自動化 See references/browser-automation.md
AI スナップショットワークフロー See references/ai-snapshot-workflow.md

実行手順

Step 0: agent-browser の確認

# インストール確認
which agent-browser

# 未インストールの場合
npm install -g agent-browser
agent-browser install

Step 1: ユーザーのリクエストを分類

リクエストタイプ 対応アクション
URL を開く agent-browser open <url>
要素をクリック スナップショット → agent-browser click @ref
フォーム入力 スナップショット → agent-browser fill @ref "text"
状態確認 agent-browser snapshot -i -c
スクリーンショット agent-browser screenshot <path>
デバッグ agent-browser --headed open <url>

Step 2: AI スナップショットワークフロー(推奨)

ほとんどの操作で、まずスナップショットを取得してから要素参照で操作します:

# 1. ページを開く
agent-browser open https://example.com

# 2. スナップショット取得(AI 向け、インタラクティブ要素のみ)
agent-browser snapshot -i -c

# 出力例:
# - link "Home" [ref=e1]
# - button "Login" [ref=e2]
# - input "Email" [ref=e3]
# - input "Password" [ref=e4]
# - button "Submit" [ref=e5]

# 3. 要素参照で操作
agent-browser click @e2           # Login ボタンをクリック
agent-browser fill @e3 "[email protected]"
agent-browser fill @e4 "password123"
agent-browser click @e5           # Submit

Step 3: 結果の確認

# 現在の状態をスナップショットで確認
agent-browser snapshot -i -c

# または URL を確認
agent-browser get url

# スクリーンショットを取得
agent-browser screenshot result.png

クイックリファレンス

基本操作

コマンド 説明
open <url> URL を開く
snapshot -i -c AI 向けスナップショット
click @e1 要素をクリック
fill @e1 "text" フォームに入力
type @e1 "text" テキストを入力
press Enter キーを押す
screenshot [path] スクリーンショット
close ブラウザを閉じる

Read the full file on GitHub · 188 lines

Files

What ships with it

2 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. 4d ago First seen · 188 lines · 53 tokens per session scan A 3414853814ba

Subscribe to this mod's changes

agent-browser is a skill published in the GitHub repository Chachamaru127/claude-code-harness (3,082 stars, last pushed 3d ago), licensed MIT. It adds 53 tokens to every session and 1,592 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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