lean-browser-use

MCP server · npm · graded 2026-10-27Source linked

Cut browser use cost by about 25% in Claude Code: fresh runner subagent, bulk reads, three guards and a token meter. One npx command

No outside reports on file

lean-browser-use fetches arbitrary web URLs and requires API keys or tokens; restrict its folder reach, network access, and credentials before installing.

Based on public adoption and transparency signals as of Oct 27, 2026. Our opinion, not a code audit or security guarantee.

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What it can access

Local filesNo local folder access notedLOW
Command executionNo shell command runner notedLOW
Network reachFetches arbitrary web URLsREVIEW
CredentialsRequires API key or tokenREVIEW
Package sourcenpm (lean-browser-use)PUBLIC

Inferred from this listing’s public package details and description. Check the project’s source before installing.

Install

npx -y lean-browser-use

All setup options ↓

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Everything known

We found nothing about this project in the sources we read (last checked 2026-10-30). That does not mean it has no problems.

0 incidents · 0 advisories · 0 news articles · 0 community threads · checked 2026-10-30

Popularity grade: D (from public signals such as stars and downloads, not a code review). Graded 2026-10-27.

Sources we read: OSV, GitHub Advisory Database, CISA Known Exploited Vulnerabilities, 44 security news feeds and our incident library. Last checked 2026-10-30.

Check a specific version →

About Lean Browser Use

Lean Browser Use is an MCP server focused on Developer tools and Web & browsing: Cut browser use cost by about 25% in Claude Code: fresh runner subagent, bulk reads, three guards and a token meter. One npx command.

It is published on npm as lean-browser-use and hosted on GitHub at aunysillyme/lean-browser-use (475 weekly npm downloads). Based on its public metadata, its operational scope includes: fetches arbitrary web urls, requires api key or token.

Setup

These use the package this listing points to. Check the project’s own instructions before running anything.

npm command

npx -y lean-browser-use

MCP client config

For Claude Desktop (claude_desktop_config.json) or Cursor (.cursor/mcp.json).

json

{
  "mcpServers": {
    "lean-browser-use": {
      "command": "npx",
      "args": [
        "-y",
        "lean-browser-use"
      ]
    }
  }
}

Why this grade

DD — High risk signals

Signal-based grade (1/7 points): public source code. This reflects adoption and transparency, not a code review.

Popularity and upkeep

21/100

Weekly npm downloads: 475
Listing last refreshed: 2026-10-28

These are public popularity signals, not a maintenance check. Look at the repository’s commit history and open issues.

Risks to watch for

Untrusted web content & prompt injection: Fetches arbitrary web pages or remote endpoints where hidden instructions could manipulate agent behavior. Restrict outbound domains and review tool outputs.
Credential & token exposure: Requires API keys or secrets in configuration. Store credentials in environment variables with read-only or minimum required scopes and rotate them regularly.
Dependency & version pinning: Distributed via npm (lean-browser-use). Pin an exact release version or commit SHA rather than floating tags so upstream updates are reviewed first.

How to lower the risk

Least-privilege permissions

Give it access only to the specific folders, accounts or projects it needs, never your whole drive or admin account.
Use a separate, limited API key or login just for this tool so you can switch it off without affecting anything else.

Network isolation

Run it on a work computer or sandbox account, not one holding personal or company-sensitive data.
If your IT team can, limit which websites and services it is allowed to contact.

Monitoring

Check its activity history or logs weekly at first, and look at what it changed or sent.
Turn on alerts for new logins or unusual usage on any account it connects to.

Red flags to watch for

It asks for more access than its job requires, or prompts you to paste passwords.
It suddenly updates with new owners, or starts contacting unfamiliar websites.

Questions

How do I install Lean Browser Use?

Run npx -y lean-browser-use in your terminal, or add the server entry to your claude_desktop_config.json or .cursor/mcp.json as shown in the Setup section on this page. Full setup docs and environment variables are in github.com/aunysillyme/lean-browser-use.

Are there security reports about Lean Browser Use?

No reports found for this package in our research (last checked 2026-10-30). Lean Browser Use currently holds Grade D (High risk signals) based on public adoption and transparency signals. Review the permissions and source repository before granting access to local files, shell commands, or API keys.

Is Lean Browser Use actively maintained?

Lean Browser Use has 475 weekly npm downloads. Our directory data was last refreshed on 2026-10-28. Check recent commit activity, release tags, and open issues at github.com/aunysillyme/lean-browser-use before pinning it in production.

What are alternatives to Lean Browser Use?

You can compare Lean Browser Use side by side with other Browser MCP servers in the Related tools section on this page, or use the Compare tool on AgentArmorHQ.

Maintain or use Lean Browser Use? Show its live grade in your GitHub README, docs site, or run a check from the terminal before you install.

AgentArmorHQ Risk Grade D for Lean Browser Use

GitHub README Markdown:

markdown

[![AgentArmorHQ Risk Grade for Lean Browser Use](https://agentarmorhq.com/api/badge/aunysillyme-lean-browser-use)](https://agentarmorhq.com/skills/aunysillyme-lean-browser-use)

HTML embed:

html

<a href="https://agentarmorhq.com/skills/aunysillyme-lean-browser-use"><img src="https://agentarmorhq.com/api/badge/aunysillyme-lean-browser-use" alt="AgentArmorHQ Risk Grade for Lean Browser Use" height="20" /></a>

Terminal check:

terminal

curl -fsSL https://agentarmorhq.com/api/cli | node --input-type=module - check "aunysillyme-lean-browser-use"

Share with your security lead

Need sign-off to use lean-browser-use? Copy this note for Slack, a ticket or a pull request.

### AgentArmorHQ Security Review Memo: lean-browser-use
- **Listing URL:** https://agentarmorhq.com/skills/aunysillyme-lean-browser-use
- **Type:** App connector
- **Risk Grade:** Grade D (High risk signals)
- **Outside Security Advisories on File:** 0

#### Permission & Blast-Radius Signals
- **Local files:** No local folder access noted
- **Command execution:** No shell command runner noted
- **Network reach:** Fetches arbitrary web URLs
- **Credentials:** Requires API key or token
- **Package source:** npm (lean-browser-use)

#### Recommended Hardened Setup
- **Command:** `npx -y --ignore-scripts lean-browser-use`
- **Controls:** Pin an exact version in `.mcp.json`, scope access to a single workspace folder, and use a least-privilege read-only token where supported.

_Based on public adoption and transparency signals as of Oct 27, 2026. Our opinion, not a code audit or security guarantee._

Key facts

Type: App connector
Publisher: aunysillyme
Source code: github.com/aunysillyme/lean-browser-use
Install command: npm install lean-browser-use
Est. context load: ~850 tokens / turn (~5 tool schemas, 0.43% of 200k context)
Popularity: 475 weekly npm downloads
Last updated: 2026-10-28
Last graded: 2026-10-27

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