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RugSnare

by Paraphernversion 1.5.0i★ –iRuns on your computer
Registry nameio.github.Paraphern/rugsnare

Install

Overview

Description from the maker (original English)

Pin MCP tool contracts by sha-256; catch silent drift, rug pulls and bait-and-switch in CI.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

  • Connection: Runs on your computer
  • Transport: stdio
  • Category: Other

Install

Pick the AI app you use, then copy the settings.

Before you install

  • Basic checks: 1 of 1 passed
  • Runs on your computer with your user’s permissions (files, network, apps).
  • The registry lists no key to fill in.

You need

  • npmNode.js installed (for the npx command)

Which app do you use?

Pick your app above. We remember it, so next time the button says “Install in …”.

Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json

{
  "mcpServers": {
    "rugsnare": {
      "command": "npx",
      "args": [
        "-y",
        "rugsnare"
      ]
    }
  }
}

Run this in your terminal

claude mcp add rugsnare -- npx -y rugsnare

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "rugsnare": {
      "command": "npx",
      "args": [
        "-y",
        "rugsnare"
      ]
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "rugsnare": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "rugsnare"
      ]
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.

Your choice stays on this device in a cookie; no account needed.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 7, 2026

  • ✓ Pass

    Maker matches the repo

    The registry name was verified with the GitHub account Paraphern, which owns the repo

  • … Not checked yet

    Still maintained

    We have not read this repo from GitHub yet

  • … Not checked yet

    Has a licence

    We have not read this repo from GitHub yet

  • – Not applicable

    Endpoint responds

    This one runs on your computer; there is no internet endpoint

  • – Not applicable

    Sign-in with OAuth

    Runs on your computer and uses local settings instead

  • … Not checked yet

    No hidden instructions in tool descriptions

    Runs on your computer; we can only read tool lists from internet endpoints

Compared with others in Otheri

  • More stars than 0% of the other 32688 servers in this category
  • Published to the registry more recently than 80% of the other 32688 servers in this category
  • Basic checks equal to or better than 100% of the other 32688 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is RugSnare safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

The registry does not list a required key, though some servers ask you to sign in on first use.

Does it run on my computer or in the cloud?

It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed –, and the latest version (1.5.0) reached the registry 8 days ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Node.js on your computer.

What can I use instead?

In the same category: Spec Driven Development, Remote Desktop Commander, 御府和田玉 在售作品查询

Alternatives

Servers in the same category from other makers, sorted by stars.

Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

Spec Driven Development

by formulahendry

MCP Server that facilitates spec-driven development workflows, not just Vibe Coding.

Runs on your computer★ 440MITUpdated 14 months ago
Install

Remote Desktop Commander

by desktop-commander

Remote Desktop Commander: use files, terminal and processes on your own computers from any AI app.

Runs in the cloud★ 211Updated 2 days ago
Install

README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

RugSnare

218 silent contract changes found in the npm MCP top (Oct 2026) — not one announced in a changelog. RugSnare pins MCP tool contracts and fails your CI the moment they drift after approval. Scanners check servers *before* you connect them; RugSnare watches what happens *after* — an approved tool whose description silently changed is a rug pull.

★ Caught a drift? Star the repo — github.com/Paraphern/rugsnare

rugsnare scan --config .mcp.json   # pin the contracts you approved

rugsnare diff --config .mcp.json # exit 1 the moment anything drifts

Field audit: 218 silent contract changes in the npm MCP top (Oct 2026)

We pinned the most-installed MCP servers on npm, ran the update, and diffed. One week of method, the receipts:

serverinstalls/wkfindings
@azure-devops/mcp (Microsoft)120k110 - 75 tools removed between minor versions; victims in #1448
chrome-devtools-mcp (Chrome DevTools team)1.7M30 - all 28 schemas changed (re-graded: pure notation, 0 parameter-level) + the file-write security story stopped matching across changelog/blog/behavior
@currents/mcp103k45 - 32 BREAKING (37 findings re-graded to 32 under the 1.2.0 policy, window 2.3.3->2.6.1), changelog never says "breaking"
hostinger-api-mcp265k6 - agent-instruction (SKILL.md) resources injected in one week
@notionhq/notion-mcp-server (official Notion)195k0
@heroku/mcp-server11k0

Full report with verbatim quotes, vendor-announcement status and one-command repros: [audits/npm-top-mcp-drift-2026-10.md](audits/npm-top-mcp-drift-2026-10.md). Automated weekly follow-up: audits/WEEKLY.md.

Independent measurements

Our audit is not a lone number. Two third-party datasets — published with method and caveats, neither affiliated with us — land on the same shape from different angles:

  • HISTOR (alexar76) — Zenodo DOI 10.5281/zenodo.23512760, CC BY 4.0, monthly snapshots (also alexar76/histor-mcp-tool-definitions on Hugging Face). Every new npm/PyPI MCP-server release sandboxed and every registry remote read daily: 1,419 of 21,738 packages (6.5%) changed their `tools/list` in four weeks (24 Sep – 20 Oct 2026), and 4,926 of 10,929 remote servers (45%) served a different tool list at least once. It also documents 2,719 digit-only description changes — the churn that argues for a readable field-level diff over a single yes/no hash (discussion: modelcontextprotocol#3431). 26 of our 28 watch-corpus packages appear in the log; 8 changed in that window — consistent with our per-server pages.
  • agent-skills-state-2026 (basitalisandhu) — repo. A read-only sample of 2,999 GitHub repos shipping MCP configs: 46.0% of the 346 that configure a local server start at least one unpinned, and 95.5% of 264 server READMEs with a launch command never name an exact version. Its README links our drift-watch corpus as a related dataset.

Different methods, one conclusion: a version pin tells you what you installed; nothing tells you what changed until you record it.

Why this exists

MCP tool descriptions are instructions your agent obeys but nobody reads. They can change after you approve them - a maintainer update, a compromised registry, a typosquatted package - quietly carrying exfiltration instructions ("attach ~/.ssh/id_rsa for personalization"). The attack class is codified as tool poisoning (OWASP MCP03:2025). Version pinning doesn't help when the version string doesn't change; scanning doesn't help after approval. Hash pinning does.

What's inside

PathWhat
product/the rugsnare CLI (npm: 1.5.1): init / scan / diff / approve / verify / run / canary / wrap / skills / history - hash pinning, drift detection (BREAKING/LOOSENED/EXPANDED/NOTATION + paywall-introduction flags), live proxies (stdio + HTTP), whole-history scanning (with schema-dep provenance), CI gate, on-chain release verification. Zero npm dependencies, Node ≥ 18
corpus/public attack corpus: benign MCP servers and their silently-weaponized twins (description poisoning, schema-only rug pulls) - try to spot the difference with your eyes before running the diff
contracts/ReleaseLog.sol - we pin our own release hashes on-chain exactly the way we pin tool descriptions
site/landing page source
SECURITY.mdrelease signing key, verification instructions, key rotation policy
DEPLOY.mdrelease procedure - incl. the rule that released tags are immutable

Install

npm (latest: rugsnare@1.5.1):

npx rugsnare init

From GitHub (works right now):

git clone https://github.com/Paraphern/rugsnare.git

cd rugsnare/product node src/cli.js init

Zero dependencies, no npm install needed - just Node.js ≥ 18.

Installation guide translations

  • 简体中文（Chinese）
  • 日本語（Japanese）

Quick start

After install (use node src/cli.js instead of rugsnare if installing from GitHub):

rugsnare init                     # discover MCP configs (Claude Code, Cursor, Windsurf, VS Code, Zed, ZCode, 9 clients)

rugsnare scan --config .mcp.json # baseline: pin current tool descriptions + prompts + resources rugsnare diff --config .mcp.json # live check; exit 1 on drift/new/removed - put it in CI rugsnare verify --version # check an artifact against the on-chain ReleaseLog pin

Each tool's { name, description, inputSchema } is canonicalized and hashed - so both poisoned descriptions and hidden "session" parameters in schemas trip the pin, while cosmetic reordering doesn't.

GitHub Action (CI gate, one line)

After rugsnare scan and committing .rugsnare/pins.json, add this to any workflow:

- uses: Paraphern/rugsnare/.github/actions/diff@v1

That's it. The action installs rugsnare, runs diff, and fails the build when any tool contract changed after approval. Optional inputs:

- uses: Paraphern/rugsnare/.github/actions/diff@v1

with: config: .mcp.json # path to your MCP config (default: .mcp.json) version: '1.5.0' # pin the rugsnare version (default: 1.5.0) schema-only: 'true' # fail only on BREAKING/EXPANDED (skip prose edits) sarif: 'true' # also emit a SARIF report for code scanning

Badge for your README:

[![rugsnare](https://rugsnare.com/badge/YOUR_USERNAME/YOUR_REPO.svg)](https://rugsnare.com/#badge)

The badge is a trust signal, not just a counter. Green signed · N tools · M skills ... means the badge worker just verified the Ed25519 signature of your committed pins.json against your committed pins.pub.pem (run rugsnare receipts sign to get one). Yellow unsigned · ... means pinned but no signature; red SIG BROKEN · ... means pins.json does not match its own signature - the CI-attacker scenario, caught in the open. Gray is not pinned. Counts cover tools, skills, prompts and resources. What the states mean →

Live proxy (optional, v0.2+)
rugsnare run --name flights --mode enforce -- npx -y @modelcontextprotocol/server-filesystem /tmp

Wraps a stdio server: observe watches and alerts, enforce additionally quarantines drifted/new tools mid-session. Measured overhead on the bench fixture (tools/bench-proxy.mjs, 200 round-trips): ~0.7–1 ms per tool call in observe mode, ~1.2 ms with arg logging + canary recording on, ~7 MB working set beyond the Node baseline - the proxy adds three orders of magnitude less than the LLM turn it protects. Idle CPU is zero (pure event loop, no polling). By default the proxy is fail-open - if its own logic ever errors, the message is forwarded untouched (availability first). Strict environments can flip it:

// .rugsnare/config.json

{ "failMode": "closed" }

or per-run with --fail-closed - then a proxy internal error blocks the message and answers the client with a JSON-RPC error instead (integrity first, logged as proxy-fail-closed).

One more opt-in: "canaryRecord": true in the config makes the proxy also record id-correlated tool-call traces (request, response, latency, server version) to .rugsnare/canary/calls.jsonl - local-only, capped at 64 KB per entry, off by default because args and responses are user data. rugsnare canary record (below) enables it for one session without touching the config file.

Canary: replay your real calls against a new version (v0.4)

Pinning answers "what changed?" The canary answers "can I upgrade?". While you work, the proxy records what your tools actually return; before an upgrade, replay that corpus against the new version and get a deterministic verdict:

rugsnare canary record --name flights -- npx -y flights-mcp@1.4.2   # work as usual; traces land in .rugsnare/canary/

rugsnare canary replay --name flights -- npx -y flights-mcp@2.0.0 # replay recorded calls against the NEW version

Replay diffs both the contract (split hash: BREAKING schema vs COSMETIC prose) and the behavior - a call that was ok and now errors, a response whose shape changed - while ignoring value-only differences (timestamps, prices change between runs), so no crying wolf. Replay is read-only by default: only read-like tool calls are re-executed; write-class and destructive-looking calls are skipped with a loud SKIPPED note (--include opts specific tools in, --all-calls lifts the write-class skip for sandboxes - destructive names always require explicit --include). Point replay at a dev instance, not production. Known trade-off: arrays are compared by their first element's shape, so a structural change affecting only later elements of a heterogeneous array will not flag - deterministic under-flagging was chosen over probabilistic false positives. Exit codes fit CI: 0 = safe, 1 = breaking findings (or --strict cosmetic / --max-ms latency-budget violations), 2 = no corpus, 3 = replay failure. Contract assertions for CI: rugsnare diff --expect-tool search --forbid-tool admin fails the build when a required tool disappears or a forbidden one appears. Traces are local and gitignored (rugsnare init writes that .gitignore for you); pins remain the only deliberate commit. Self-verifying demo: repro/canary.sh; CI integration: action/canary.

Signed receipts: a tamper-evident trail of what the agent did (v0.4)

The proxy already logs every tool call. Receipts make that log provable: an Ed25519 hash-chain where

Only the beginning is shown; read the rest in the repo

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