Is skill@1.2.2 safe to install?

skill@1.2.2

VERIFIED

Publisher claims: "Agent Skill that teaches AI coding agents (Claude Code, Cursor, Copilot, Codex) to build, debug, and publish browser extensions for Chrome, Edge, Firefox, Safari, and every Chromium- or Gecko-based browser (Brave, Opera, Vivaldi, Yandex, Waterfox, Zen, Fl" Observed in sandbox: no network, touches nothing outside the project, writes no memory.

Registry npm (MCP server)Publisher extension.dev · joined 10 days agoInstalls 898Last detonated 2 h ago

$claude mcp add skill -- npx -y @extension.dev/skill

Watch Report an issue

Is [email protected] safe to install?

KillerSkills ran it in the KillerSkills honeypot sandbox (1 scenario) on 2026-11-06 and scored it 88/100 (Verified). It did what it claims and nothing else we could detect: no undeclared network egress, no credential reads, no persistent instruction writes. Summary: no network, touches nothing outside the project, writes no memory.

Behavior trace

Honeypot run · 0 s · 1 scenarios · 0 deviations

t+CategoryObserved action

0.0sprocessno install scripts in bundle

0.0sprocessscript backend runs setup only

0.0sprocessno install scripts to re-run

Static findings

LOW

Instructs the agent to modify its persistent memory or instruction filesREADME.md:106 · Instructs the agent to modify its persistent memory or instruction files · informational: not an instruction fileFix: Remove the text that addresses the agent rather than the reader; describe behavior, do not instruct.

AST01

MEDIUM

npx invocation of non-well-known packageskills/extension-dev/SKILL.md:39 · npx invocation of non-well-known package — may execute untrusted codeFix: Pin versions and sources; vendor anything fetched at install time.

AST06

MEDIUM

npx invocation of non-well-known packageskills/extension-dev/SKILL.md:65 · npx invocation of non-well-known package — may execute untrusted codeFix: Pin versions and sources; vendor anything fetched at install time.

AST06

Cost to the agent

Instructions loaded

≈6,295 tok

1 file · 22 in bundle

Tokens estimated at four characters each. Skills load their instruction text when triggered; the figure is what that costs.

Known vulnerabilities

No advisories in OSV for @extension.dev/skill@1.2.2 as of 1 h ago. This is the package itself, not its dependencies.