defender: Open source prompt injection protection for Agents calling tools (via MCP, CLI or direct function calling)

by StackOneHQ · MCP Server · ★ 134

Last updated: · Indexed by AgentSkillsHub · Auto-synced every 8h

How to install defender

npm install @stackone/defender

Taken from the project's README on GitHub.

Security audit verdict: SAFE · quality 73/100

None of the 42 rules matched — no credential harvesting, no data exfiltration, no curl-pipe-shell installer. Scanned against 42 published rules built on the SlowMist agent-security taxonomy, refreshed every 8 hours.

The quality score combines nine heuristic checks of the repo and its README: completeness, clarity, specificity, examples, structure, agent readiness, step-by-step content, instruction quality and security notes. It rates how well the project explains itself to an agent, not the code.

ai-securityindirect-prompt-injectionllm-securitymcp-securityprompt-injectionprompt-injection-defenseprompt-injection-detectionprompt-injection-protection

Quick Facts

Stars134
Forks13
LanguageTypeScript
CategoryMCP Server
LicenseApache-2.0
Quality Score73/100
Last Updated2026-11-07
Created2026-02-13
Platformscli, mcp, node
Est. Tokens~17k

About defender

<img src="https://img.shields.io/badge/model-22MB-047B43

Compatible Skills

These tools work well together with defender for enhanced workflows:

defender alternative? Top 6 similar tools

Looking for a defender alternative? If you're comparing defender with other mcp server tools, these 6 projects are the closest alternatives on Agent Skills Hub — ranked by topic overlap, star count, and community traction.

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    Security toolkit for AI agents. Scan your machine for dangerous skills and MCP configs, monitor for supply cha

  • agent-security-scanner-mcp by sinewaveai · ⭐ 121

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  • vestige by samvallad33 · ⭐ 659

    Think before doing, prove before saving. Vestige is the local-first cognitive operating system and determinist

  • openclaw-skills-security by UseAI-pro · ⭐ 73

    Curated, security-first OpenClaw skills (Markdown-based). Security audit skills - detect prompt injection, sup

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How this security grade is produced

Grades come from a rule-based scan built on the SlowMist agent-security taxonomy: 42 published rules, covering credential harvesting, data exfiltration, curl | sh installers and more. It is a first-layer scan, not a manual audit — we say so rather than overstate it.

The scale of the problem is documented independently: Liu et al. (2026), in a study of 31,132 agent skills, report that 26.1% contain security vulnerabilities. Our own full-catalog census is published as a citable open dataset.

Sources & who's responsible:

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