Sentinel MCP Server (@oppialabs/sentinel-mcp)

MCP server that exposes Sentinel governance and payment tooling to MCP clients (Claude Code, Cursor, etc.) over stdio.

The server provides 4 tools:

1. request_payment — run a payment request through Sentinel governance (consensus + policy), with optional x402 resource fetch.
2. get_policy — read current spending policy.
3. get_transactions — fetch recent governed transactions.
4. register_agent — register a hosted voting agent (OpenAI/Anthropic) in Sentinel.

Requirements

• Node.js 20+
• A Sentinel API key (x-sentinel-key), available from: https://app.sentinel.xyz/dashboard/settings

Environment variables

Create apps/shieldpay-mcp/.env (or set env vars in your MCP client config):

# Required
SENTINEL_API_KEY=sk_live_...

# Optional
SENTINEL_API_URL=
SENTINEL_AGENT_ID=claude-code

Defaults in code:

• SENTINEL_AGENT_ID defaults to claude-code

Local development

From repo root:

npm install
npm run dev -w shieldpay-mcp

Build + run:

npm run build -w shieldpay-mcp
npm run start -w shieldpay-mcp

MCP client setup

Claude Code

Install from npm:

claude mcp add shieldpay -- npx @oppialabs/sentinel-mcp -e SENTINEL_API_KEY=sk_live_...

Or run local build:

claude mcp add shieldpay \
  --scope user \
  -e SENTINEL_API_KEY=sk_live_... \
  -e SENTINEL_API_URL=http://localhost:4000 \
  -e SENTINEL_AGENT_ID=claude-code \
  -- node /absolute/path/to/sentinel/apps/shieldpay-mcp/dist/index.js

Tool details

request_payment

Submits a payment intent to:

• POST /api/proxy/settle

Inputs:

• vendor (string)
• amount (number, USDC)
• task_description (string)
• asset_code (string, default USDC)
• resource_url (optional URL to x402-protected resource)
• resource_method (GET or POST, default GET)
• resource_body (optional JSON object for POST)

Returns approved/rejected decision, vote summaries, tx/escrow metadata, and optional fetched resource payload.

get_policy

Reads policy from:

• GET /api/me/policy

Formats limits and blocked vendors for quick operator review.

get_transactions

Reads transaction history from:

• GET /api/me/transactions?limit=... (1-50, default 10)

Returns a compact timeline of recent approved/rejected requests.

register_agent

Registers a hosted LLM voting agent via:

• POST /api/agents

Inputs:

• agent_id
• provider (openai or anthropic)
• api_key
• model (default gpt-4o-mini)
• system_prompt
• description (optional)

Error behavior

• Missing SENTINEL_API_KEY returns explicit tool errors.
• Upstream API failures are returned with status details.
• For rejected payments, vote reasons are included when available.