Is the guardrails MCP server free to use?

Yes. guardrails is listed on AllMCPs as a free, open Model Context Protocol server you can install into Claude Desktop, Cursor, or any MCP-compatible client.

Is the guardrails MCP server free to use?

Yes. guardrails is listed on AllMCPs as a free, open Model Context Protocol server you can install into Claude Desktop, Cursor, or any MCP-compatible client.

Guardrails

AI Agent Guardrails MCP server - security layer

Quick Install

Automated & IDE Setup

Copy the AI prompt to install this server into Claude Code, Cursor, or another agent — or use 1-click editor setup below.

Add to Cursor Add to VS Code

Manual Client & Custom JSON ConfigExpand JSON ▾

Install Config Generator

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claude_desktop_config.json

{
  "mcpServers": {
    "guardrails": {
      "command": "npx",
      "args": [
        "-y",
        "https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT"
      ]
    }
  }
}

💡 Paste into ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows)

Capabilities & Tool Schemas (6)Self-reported

Inspect callable tools, capabilities, and parameters exposed to AI agents by Guardrails.

validate_input

Validate and sanitize incoming requests through all guardrail checks

filter_output

Filter and redact sensitive data (PII, secrets, credentials) from responses

check_policy

Evaluate a request against security policies (RBAC, resource access, quotas)

get_audit_logs

Query the audit log with filtering by type, user, time range

get_stats

Get engine statistics including active users, block rate, request counts

update_config

Update guardrail configuration at runtime

Documentation Overview

guardrails-mcp-server

[!License: MIT](https://opensource.org/licenses/MIT) [!MCP](https://modelcontextprotocol.io) [!Node.js](https://nodejs.org)

MCP server for AI agent security guardrails. Provides input validation, prompt injection detection, PII redaction, output filtering, policy enforcement, rate limiting, and comprehensive audit logging.

Tools

Tool	Description
`validate_input`	Validate and sanitize incoming requests through all guardrail checks
`filter_output`	Filter and redact sensitive data (PII, secrets, credentials) from responses
`check_policy`	Evaluate a request against security policies (RBAC, resource access, quotas)
`get_audit_logs`	Query the audit log with filtering by type, user, time range
`get_stats`	Get engine statistics including active users, block rate, request counts
`update_config`	Update guardrail configuration at runtime

Security Features

Prompt Injection Detection -- 12 regex patterns for jailbreak, DAN mode, system prompt override
PII Detection and Redaction -- SSN, credit card, email, phone, IP, API keys, AWS keys, JWT, passwords, private keys, connection strings
Malicious Code Blocking -- eval, exec, subprocess, child_process, shell injection
Policy Engine -- Block sensitive paths, dangerous tools, unauthenticated destructive ops, URL allowlist, maintenance windows
Rate Limiting -- Per-user sliding window (configurable requests/minute)
Audit Logging -- Timestamped events with metrics, log rotation, external handler support

Install

Terminal

npm install

Configuration

config.json

{
  "mcpServers": {
    "guardrails": {
      "type": "stdio",
      "command": "node",
      "args": ["/path/to/guardrails-mcp-server/index.js"]
    }
  }
}

Project Structure

Code

src/engine/GuardrailsEngine.js    # Core orchestration
src/validators/InputValidator.js   # Prompt injection and PII detection
src/filters/OutputFilter.js        # Redaction and harmful content blocking
src/policies/PolicyEngine.js       # RBAC, quotas, maintenance windows
src/audit/AuditLogger.js           # Event logging and metrics

License

MIT

Related MCP Servers

View all in Security View all alternatives

Frequently Asked Questions about Guardrails

Add the following block to your claude_desktop_config.json under mcpServers: "mcpServers": { "guardrails": { "command": "npx", "args": ["-y", "guardrails"] } }

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Technical Specs & Signals

CategorySecurity

5/5 checks healthy over the last 6h

49Quality signal: Fair · 49/100How this signal is calculated ▾

Server availabilityNot measured

Not scored for repo-hosted servers — we can't reach the running server, only its GitHub page. Hosted MCP endpoints are health-checked live.

Verified ownership10/20

Documentation & tools23/30

Adoption & activity4/15

Community engagement0/10

A guidance signal from public completeness & health data — not a user rating. New listings start lower and rise as they add docs, get verified, and grow adoption. Signals we can't observe for a listing are skipped, not counted against it.

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More in 🔒 Security →Best MCP servers for Security →Alternatives to Guardrails →Install in Claude Desktop Install in Cursor Install in VS Code

{ "mcpServers": { "guardrails": { "command": "npx", "args": [ "-y", "https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT" ] } } }