core-api

core-api is a skill for Claude Code, Codex from MadAppGang/magus. It costs 34 tokens per session (7,346 once invoked), scanned A, original, MIT.

A reference guide for the browser tools provided by the Browser Use add-on, including their inputs, results, and session rules.

In plain words
What is it for?
Use it when navigating, clicking, typing, reading page structure or content, running browser actions, taking screenshots, scrolling, or switching tabs.
Why use it?
It gives an agent the information needed to choose and use browser actions correctly.

Skill for Claude CodeCodex

Part of the browser-use plugin — 6 skills 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/madappgang/magus/core-api
Any agent
npx skills add MadAppGang/magus --skill core-api
Clone the repo
git clone --depth 1 https://github.com/MadAppGang/magus

Made for: Claude Code, Codex.

Or install browser-use, the plugin that ships this one along with the rest of its 6 skills.

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 core-api

README.md
[![agentmods](https://agentmods.dev/badge/skills/madappgang/magus/core-api.svg)](https://agentmods.dev/skills/madappgang/magus/core-api)
Your own site
<a href="https://agentmods.dev/skills/madappgang/magus/core-api"><img src="https://agentmods.dev/badge/skills/madappgang/magus/core-api.svg" alt="Measured on agentmods" height="20"></a>
Per session 34 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 7,346 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 $0.00034 $0.07346
Opus 5 $0.00017 $0.03673
Sonnet 5 $0.00007 $0.01469
Haiku 4.5 $0.00003 $0.00735

Measured 4d ago against content hash 21bee9204c19, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

core-api 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.

plugins/browser-use/skills/core-api/SKILL.md · 735 lines

How it starts

The opening of the file, as written. The whole thing — 735 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Browser Use Core API

Reference for the MCP tools exposed by the Browser Use plugin: the upstream Browser Use set plus ten Magus-specific additions. All are accessed via mcp__browser-use__<tool_name>. The authoritative list is whatever the server registers at runtime, so check there rather than counting this table.


1. Quick Reference Table

Tool Purpose Requires session_id?
browser_navigate Navigate to URL (creates session) No (creates it)
browser_click Click element by DOM index Yes
browser_type Type text into an input element Yes
browser_get_state Get full DOM element map with indices Yes
browser_extract_content LLM-powered semantic content extraction Yes
browser_get_html Raw HTML (full page or CSS selector) Yes
browser_screenshot Capture viewport or full-page screenshot Yes
browser_scroll Scroll the page up, down, left, right Yes
browser_go_back Navigate back in browser history Yes
browser_list_tabs List all open tabs in a session Yes
browser_switch_tab Switch to a tab by tab_id Yes
browser_close_tab Close a specific tab Yes
browser_list_sessions List all active browser sessions No
browser_close_session Close session and release browser resources Yes
retry_with_browser_use_agent Autonomous LLM agent for complex tasks No (creates session)
browser_export_session Export cookies + localStorage to JSON file Yes
browser_import_session Restore session from exported JSON file No (creates session)
browser_run_script Run a standalone Python script as a subprocess (own browser) No
browser_evaluate Run JS in the live page and return its result (CDP) No (uses current)
browser_press_key Press a key/shortcut (e.g. Meta+a, Enter, Escape) No (uses current)
browser_keyboard Batch keys + insert literal text via CDP No (uses current)
browser_focus Focus any element by CSS selector (incl. hidden inputs) No (uses current)
browser_doctor Preflight: Python / deps / Chromium / API keys No

Read the full file on GitHub · 735 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. 4d ago First seen · 735 lines · 34 tokens per session scan A 21bee9204c19

Subscribe to this mod's changes

core-api is a skill published in the GitHub repository MadAppGang/magus (9 stars, last pushed yesterday), licensed MIT. It adds 34 tokens to every session and 7,346 once invoked, about $0.0002 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 2026-08-31.

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