package-verify-mcp

Catch hallucinated and typosquatted npm packages before your coding agent installs them.

An MCP server that verifies an npm package name is real and safe before Claude, Cursor, or any agent runs npm install. AI agents routinely invent plausible-sounding package names ("slopsquatting"), and attackers pre-register those exact names with malware — one hallucinated package (react-codeshift) spread into 237 repos. This server is the guardrail.

Why this exists

An agent confidently writes import x from "some-plausible-pkg" and then installs it. If that name doesn't exist, best case you get an error; worst case a squatter is waiting there with a postinstall script. Checking is one registry call — this makes the agent do it every time.

Tools

Tool	What it does
verify_package	Verdict for one name — SAFE / CAUTION / SUSPICIOUS / DOES_NOT_EXIST — from existence, first-publish age, weekly downloads, deprecation, and edit-distance to popular packages (typosquat detection).
verify_packages	Batch check — pass every dependency in a proposed change; flagged names sort to the top.

Uses only the public npm registry + downloads API. No key.

What the verdicts mean

• ✅ SAFE — exists, established (age + downloads), not a near-miss of a popular name.
• ⚠️ CAUTION — exists but young, low-traffic, deprecated, or a similar-but-established name. Confirm intent.
• 🛑 SUSPICIOUS — one or two edits from a popular package and young/low-traffic: a classic typosquat. Don't install without confirming.
• ❌ DOES_NOT_EXIST — not on npm. Hallucination signature — do not install; suggestions for the likely intended name are included.

Quick start

npx package-verify-mcp

Claude Code

claude mcp add package-verify -- npx -y package-verify-mcp

Claude Desktop / Cursor / Windsurf / any MCP client

{
  "mcpServers": {
    "package-verify": {
      "command": "npx",
      "args": ["-y", "package-verify-mcp"]
    }
  }
}

Pairs well with a rule like "Before adding any npm dependency, verify it with package-verify."

Example prompts

• "Verify react-hook-forms before you install it." (→ 🛑 typosquat of react-hook-form)
• "Check all the packages in this package.json diff with package-verify."
• "Is @types/node-fetch a real package?"

Config

Env var	Default	Purpose
NPM_REGISTRY	https://registry.npmjs.org	Registry for existence/metadata.
NPM_API	https://api.npmjs.org	Downloads API for weekly-download signal.

How it works

package name
   │
   ├─ registry GET  ── exists? first-publish date, latest, deprecated, repo
   ├─ downloads API ── weekly downloads (traffic/trust signal)
   └─ edit-distance vs bundled popular-package list ── typosquat detection
        └─► SAFE / CAUTION / SUSPICIOUS / DOES_NOT_EXIST + reasons + suggestions

Caveats

• This is a hallucination / typosquat tripwire, not a full security scanner — it won't analyze package contents (use Socket/npq for deep supply-chain analysis). It answers "is this name real and plausibly the one you meant."
• The popular-package reference list is curated, not exhaustive; extend src/popular.ts for your stack.

Develop

npm install
npm run build
node dist/index.js

License

MIT © Anicodeth