CuratedMCP Sentinel

Local-first action firewall for MCP servers.

Sentinel is CuratedMCP's enforcement layer that intercepts MCP tool calls before execution, evaluates them against JSON policy rules, logs all actions locally in SQLite, and optionally requires approval before continuing.

Installation

npm install -g @curatedmcp/sentinel

Quick Start

1. Run as a Proxy

sentinel proxy -- npx some-mcp-server

This wraps your MCP server and starts the dashboard at http://localhost:4242.

2. Visit the Dashboard

Open http://localhost:4242 in your browser to:

View recent actions
Approve/reject pending tool calls
Manage policy rules
See blocked actions

CLI Commands

Policy Management

# List all active policies
sentinel policy list

# Add a blocking rule
sentinel policy add --name "Block Dangerous Tools" --tool "*exec*" --action BLOCK --severity CRITICAL

# Remove a rule
sentinel policy remove rule-id-here

Configuration

# Set log retention (in minutes)
sentinel retention 1440  # 24 hours

# Open dashboard standalone
sentinel dashboard --port 4242

Policy Rules

Policies match on three criteria:

serverName — Glob pattern (e.g., *stripe*, exact-name)
toolName — Glob pattern (e.g., *delete*, run_*)
argumentContains — String array (optional, block if any match in args)

Actions

ALLOW — Pass through immediately
BLOCK — Reject with error message
REQUIRE_APPROVAL — Pause and wait for dashboard approval

Severity Levels

CRITICAL — Security-sensitive action
WARNING — Elevated permission action
INFO — Informational only

Example Policies

# Block shell tool
sentinel policy add --name "No Shell" --tool "*shell*" --action BLOCK

# Require approval for file operations
sentinel policy add --name "File Ops Approval" --tool "*file*" --action REQUIRE_APPROVAL --severity WARNING

# Allow verified stripe tool
sentinel policy add --name "Stripe Allowed" --server stripe-mcp --tool "*" --action ALLOW

Local Storage

All data remains local by default:

~/.sentinel/policy.json — Policy rules
~/.sentinel/actions.db — SQLite action log
~/.sentinel/config.json — Configuration

No cloud sync happens without explicit opt-in (via --key).

License Integration

Sentinel integrates with CuratedMCP licensing for optional features:

# Provide your CuratedMCP license key
sentinel proxy --key cmcp_xxxx

What's Included

✅ Local policy enforcement
✅ Action logging & audit trail
✅ Approval workflows
✅ Local dashboard

Premium Features (with License)

📊 Cloud sync to CuratedMCP dashboard
📧 Email alerts for blocked actions
🔔 Slack/webhook notifications
📈 Advanced analytics

See CuratedMCP Pricing for details.

Roadmap

Remote policy distribution
Team collaboration & approval chains
Cloud sync with encryption
Slack/webhook integrations
Advanced anomaly detection
Multi-MCP orchestration

Architecture

Client (Claude, Cursor, etc.)
    ↓
Sentinel Proxy ← Policy Engine
    ↓
MCP Server

Every CallToolRequest is:

Intercepted by Sentinel
Evaluated against policies
Logged to SQLite
Either allowed, blocked, or held for approval
Forwarded to downstream server (if allowed)

License

MIT

Made with ❤️ by CuratedMCP
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