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The Sentrail CLI is a local MCP proxy that sits between your coding agent and its tools. Every tools/call — including shell commands — is classified and checked against your Sentrail workspace policies before it executes. This is how rm -rf, git push --force, DROP TABLE, and other destructive commands get blocked or approval-gated. The cloud MCP gateway (mcp-gate) only sees JSON-RPC calls to a connected upstream server; it cannot intercept shell commands. The local interceptor can.

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Quick start (under 2 minutes)

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1. Install

npm install -g sentrail
Requires Node.js 18 or later.

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2. Initialize

sentrail init
The CLI prompts for:
  • Your Sentrail API key (agk_…)
  • Your workspace ID
  • The upstream MCP server URL the proxy should forward allowed calls to
After setup, it prints the MCP config snippet for the next step.

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3. Add the proxy to your agent

Paste the config snippet into your agent’s MCP settings: 
{
  "mcpServers": {
    "sentrail": {
      "url": "http://localhost:3773"
    }
  }
}
For Claude Code: ~/.claude/mcp_servers.json or .claude/mcp_servers.json in the project root. For Cursor: Cursor Settings → MCP or ~/.cursor/mcp.json.

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4. Start the interceptor

sentrail start
The proxy runs in the foreground and logs every decision with color coding:
  • Green → allowed, forwarded to upstream
  • Red → blocked by policy
  • Yellow → held for human approval

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5. Verify with the built-in demo

sentrail demo
The demo runs four simulated agent actions — rm -rf, git push --force, DROP TABLE, and cat README.md — and shows the Sentrail decision for each. No real commands are executed and no cloud connection is required.

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How decisions are made

Agent (Claude Code / Cursor / Codex)
        │  tools/call
        ▼
Sentrail local proxy (localhost:3773)
        │
        ├─ classify command (shell classifier: rm -rf → file.delete_recursive / critical)
        │
        ├─ POST /evaluate-action → Sentrail cloud policy engine
        │
        ├─ allow    → forward to upstream MCP server, return result
        ├─ block    → return MCP error -32000 (🛑 Blocked by Sentrail)
        └─ require_approval → prompt in terminal, poll for reviewer decision
If the Sentrail cloud is unreachable, the proxy fails closed: write actions are blocked, read-only actions are allowed.

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Supported agents

Any MCP-compatible client, including:
  • Claude Code
  • Cursor
  • Codex
  • Custom agents using the MCP protocol over HTTP