MCP

MCP server

POST/mcp

The MCP server agents connect to as tools: Streamable HTTP, JSON-RPC 2.0, protocols 2025-06-18, 2025-03-26 and 2024-11-05, stateless. Authenticate with an agent key or an OAuth access token; authentication comes before anything else, including initialize.

Tools: authorize_action, request_payment, request_personal_data, check_action_status, explain_decision and settle_action. Batches are not supported.

#Authentication

Agent key

An agent-scoped key (ask_...) bound to exactly one agent, or an OAuth access token (aat_...) issued to an MCP client for that agent, sent as Authorization: Bearer. An agent key may ask, poll and settle. It can never approve, widen a mandate or lift a freeze.

Request

curl -X POST "https://immiscible.fly.dev/mcp" \
  -H "authorization: Bearer $IMMISCIBLE_AGENT_KEY" \
  -H "content-type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "tools/call",
    "params": {
      "name": "request_payment",
      "arguments": {
        "amount": 4200,
        "currency": "GBP",
        "merchant": {
          "domain": "grocer.example"
        },
        "summary": "Weekly shop"
      }
    }
  }'

const res = await fetch('https://immiscible.fly.dev/mcp', {
  method: 'POST',
  headers: {
    authorization: `Bearer ${process.env.IMMISCIBLE_AGENT_KEY}`,
    'content-type': 'application/json',
  },
  body: JSON.stringify({
    jsonrpc: '2.0',
    id: 1,
    method: 'tools/call',
    params: {
      name: 'request_payment',
      arguments: {
        amount: 4200,
        currency: 'GBP',
        merchant: {
          domain: 'grocer.example',
        },
        summary: 'Weekly shop',
      },
    },
  }),
});
const data = await res.json();
console.log(res.status, data);

import os
import requests

res = requests.post(
    "https://immiscible.fly.dev/mcp",
    headers={
        "authorization": f"Bearer {os.environ['IMMISCIBLE_AGENT_KEY']}",
        "content-type": "application/json",
    },
    json={
        "jsonrpc": "2.0",
        "id": 1,
        "method": "tools/call",
        "params": {
            "name": "request_payment",
            "arguments": {
                "amount": 4200,
                "currency": "GBP",
                "merchant": {
                    "domain": "grocer.example",
                },
                "summary": "Weekly shop",
            },
        },
    },
)
print(res.status_code, res.json())