prompt-rejector

MCP server · npm · ★ 2 · graded 2026-10-22Source linked

Security gateway for LLM agents: detects prompt injections, jailbreaks, lethal-trifecta agent configurations, Hugging Face model risks, MCP tool poisoning, and classic web vulnerabilities. Ships a CLI, typed JavaScript SDK, MCP server (11 tools), and REST

No outside reports on file

prompt-rejector is distributed via npm (prompt-rejector); review its source code, dependencies, and requested permissions before use.

Based on public adoption and transparency signals as of Oct 22, 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 reachLocal or standard API callsLOW
CredentialsNo API token requiredLOW
Package sourcenpm (prompt-rejector)PUBLIC

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

Install

npx -y prompt-rejector

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 2026-10-22.

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 Prompt Rejector

Prompt Rejector is an MCP server focused on Developer tools and Web & browsing: Security gateway for LLM agents: detects prompt injections, jailbreaks, lethal-trifecta agent configurations, Hugging Face model risks, MCP tool poisoning, and classic web vulnerabilities. Ships a CLI, typed JavaScript SDK, MCP server (11 tools), and REST.

It is published on npm as prompt-rejector and hosted on GitHub at revsmoke/promptrejectormcp (2 GitHub stars, 47 weekly npm downloads, last repository push on 2026-10-01). Based on its public metadata, it operates with standard local or API scope without broad shell execution flags noted.

Setup

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

npm command

npx -y prompt-rejector

MCP client config

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

json

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

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

23/100

GitHub stars: 2
Weekly npm downloads: 47
Listing last refreshed: 2026-10-29

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

Risks to watch for

Dependency & version pinning: Distributed via npm (prompt-rejector). 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 Prompt Rejector?

Run npx -y prompt-rejector 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/revsmoke/promptrejectormcp.

Are there security reports about Prompt Rejector?

No reports found for this package in our research (last checked 2026-10-30). Prompt Rejector 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 Prompt Rejector actively maintained?

Prompt Rejector has 2 GitHub stars and 47 weekly npm downloads, with its latest repository commit pushed on 2026-10-01. Our directory data was last refreshed on 2026-10-29. Check recent commit activity, release tags, and open issues at github.com/revsmoke/promptrejectormcp before pinning it in production.

What are alternatives to Prompt Rejector?

Compare Prompt Rejector side by side with similar MCP servers in the Related tools section on this page, or browse all MCP servers on AgentArmorHQ.

Maintain or use Prompt Rejector? 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 Prompt Rejector

GitHub README Markdown:

markdown

[![AgentArmorHQ Risk Grade for Prompt Rejector](https://agentarmorhq.com/api/badge/revsmoke-promptrejectormcp)](https://agentarmorhq.com/skills/revsmoke-promptrejectormcp)

HTML embed:

html

<a href="https://agentarmorhq.com/skills/revsmoke-promptrejectormcp"><img src="https://agentarmorhq.com/api/badge/revsmoke-promptrejectormcp" alt="AgentArmorHQ Risk Grade for Prompt Rejector" height="20" /></a>

Terminal check:

terminal

curl -fsSL https://agentarmorhq.com/api/cli | node --input-type=module - check "revsmoke-promptrejectormcp"

Share with your security lead

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

### AgentArmorHQ Security Review Memo: prompt-rejector
- **Listing URL:** https://agentarmorhq.com/skills/revsmoke-promptrejectormcp
- **Type:** App connector
- **Risk Grade:** Grade D (High risk signals)
- **Outside Security Advisories on File:** 0
- **Public Adoption:** 2 GitHub stars, 47 weekly npm downloads

#### Permission & Blast-Radius Signals
- **Local files:** No local folder access noted
- **Command execution:** No shell command runner noted
- **Network reach:** Local or standard API calls
- **Credentials:** No API token required
- **Package source:** npm (prompt-rejector)

#### Recommended Hardened Setup
- **Command:** `npx -y --ignore-scripts prompt-rejector`
- **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 22, 2026. Our opinion, not a code audit or security guarantee._

Key facts

Type: App connector
Publisher: revsmoke
Source code: github.com/revsmoke/promptrejectormcp
Install command: npm install prompt-rejector
Est. context load: ~900 tokens / turn (~5 tool schemas, 0.45% of 200k context)
Popularity: 2 GitHub stars, 47 weekly npm downloads
Last updated: 2026-10-29
Last graded: 2026-10-22

Community

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