agent-browser

agent-browser is a skill for Claude Code, Codex from harnessclaw/harnessclaw-engine. It costs 108 tokens per session (6,475 once invoked), scanned A, a copy of agent-browser, Apache-2.0.

A command-line browser controller for AI agents. It can open web pages, inspect their controls, enter text, click buttons, wait for changes, take screenshots, and extract information.

In plain words
What is it for?
Use it to test web apps, fill out forms, navigate sites, capture screenshots, or collect information from pages.
Why use it?
It lets an agent perform and check browser-based tasks instead of only describing what a user should click.

Skill for Claude CodeCodex

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

Made for: Claude Code, Codex.

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/harnessclaw/harnessclaw-engine/agent-browser.svg)](https://agentmods.dev/skills/harnessclaw/harnessclaw-engine/agent-browser)
Your own site
<a href="https://agentmods.dev/skills/harnessclaw/harnessclaw-engine/agent-browser"><img src="https://agentmods.dev/badge/skills/harnessclaw/harnessclaw-engine/agent-browser.svg" alt="Measured on agentmods" height="20"></a>
Per session 108 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 6,475 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 77% copy Near-identical to another mod 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 $0.00108 $0.06475
Opus 5 $0.00054 $0.03238
Sonnet 5 $0.00022 $0.01295
Haiku 4.5 $0.00011 $0.00647

Measured 5d ago against content hash 9d5432574cff, 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.

The scan reads SKILL.md. This mod also ships 3 executable files (templates/authenticated-session.sh, templates/capture-workflow.sh, templates/form-automation.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Origin

This is a copy

77% identical to agent-browser — 190 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.

internal/engine/agent/builtin/browser_agent/resources/agent-browser/SKILL.md · 748 lines

How it starts

The opening of the file, as written. The whole thing — 748 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Browser Automation with agent-browser

The CLI uses Chrome/Chromium via CDP directly. Install via npm i -g agent-browser, brew install agent-browser, or cargo install agent-browser. Run agent-browser install to download Chrome. Run agent-browser upgrade to update to the latest version.

Core Workflow

Every browser automation follows this pattern:

  1. Navigate: agent-browser open <url>
  2. Snapshot: agent-browser snapshot -i (get element refs like @e1, @e2)
  3. Interact: Use refs to click, fill, select
  4. Re-snapshot: After navigation or DOM changes, get fresh refs
agent-browser open https://example.com/form
agent-browser snapshot -i
# Output: @e1 [input type="email"], @e2 [input type="password"], @e3 [button] "Submit"

agent-browser fill @e1 "[email protected]"
agent-browser fill @e2 "password123"
agent-browser click @e3
agent-browser wait --load networkidle
agent-browser snapshot -i  # Check result

Command Chaining

Commands can be chained with && in a single shell invocation. The browser persists between commands via a background daemon, so chaining is safe and more efficient than separate calls.

# Chain open + wait + snapshot in one call
agent-browser open https://example.com && agent-browser wait --load networkidle && agent-browser snapshot -i

# Chain multiple interactions
agent-browser fill @e1 "[email protected]" && agent-browser fill @e2 "password123" && agent-browser click @e3

# Navigate and capture
agent-browser open https://example.com && agent-browser wait --load networkidle && agent-browser screenshot page.png

When to chain: Use && when you don't need to read the output of an intermediate command before proceeding (e.g., open + wait + screenshot). Run commands separately when you need to parse the output first (e.g., snapshot to discover refs, then interact using those refs).

Handling Authentication

When automating a site that requires login, choose the approach that fits:

Read the full file on GitHub · 748 lines

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 · 748 lines · 108 tokens per session scan A 9d5432574cff

Subscribe to this mod's changes

agent-browser is a skill published in the GitHub repository harnessclaw/harnessclaw-engine (271 stars, last pushed 5d ago), licensed Apache-2.0. It adds 108 tokens to every session and 6,475 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. It is 77% identical to agent-browser, differing in 190 lines, and is treated as a copy.

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