# Sentinel402 RCP/1 Retrieval Server

> Sentinel402 RCP/1 Retrieval Server is a paid API for AI agents from pii-guardrail.chronokey.workers.dev, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-12).

Retrieves live, citable data (crypto prices, weather, GitHub activity, sports scores, FX rates, Hacker News, Wikipedia, stocks, news, geolocation, npm/pypi packages, ENS names) via sparse-mode RCP/1 protocol, paid per-call over x402.

## Facts

- Endpoint: POST https://pii-guardrail.chronokey.workers.dev/rcp/retrieve?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/sentinel402-rcp-1-retrieval-server-a757c695
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_c41T8dcDMoDlc6Wv6m8P8

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability sentinel402-rcp-1-retrieval-server-a757c695 -d '<json body>'
```

Example prompt: What's the current Bitcoin price right now? Use sparse mode retrieval and give me up to 5 results with citations.

## When to prefer this

Choose this endpoint when you need live, citable, structured data across a broad set of domains (crypto, weather, FX, sports, GitHub, news, wiki, stocks, geo, packages, ENS) in a single unified RCP/1 interface with per-call micropayment via x402. Prefer it over domain-specific APIs when you want citation URIs alongside data, when you need routing across multiple data types from one call, or when you are building an agent that pays per query rather than managing multiple API keys.

## Known failure modes

- Query routed to wrong collection if natural-language parsing is ambiguous (low routingConfidence)
- dense or hybrid mode requested returns error -32005 (only sparse is supported)
- Payment not attached or invalid x402 token returns 402 Payment Required
- k out of range (must be 1-50) returns validation error
- Upstream data source (Binance, weather API, etc.) unavailable causes stale or missing hits
- Unknown collection enum value causes schema validation failure

## How this service works

Paid tools for AI agents over x402: a PII and secret guardrail that scans outbound payloads, live citable data (crypto, weather, GitHub, sports, FX), and an RCP/1 retrieval server backed by that live data.

## Output

A JSON-RPC 2.0 response containing a `result.hits` array, each hit having an `id`, `text` (human-readable sentence with the data), `score`, `meta` (structured fields like priceUsd, symbol, kind), and a `citation` object with `uri` and `title`. The `_meta` object includes query routing details, collection name, upstream source, freshness in seconds, and routing confidence score.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "jsonrpc",
      "method"
     ],
     "properties": {
      "id": {
       "type": [
        "string",
        "number"
       ]
      },
      "method": {
       "enum": [
        "initialize",
        "info",
        "catalog/list",
        "ping",
        "retrieve"
       ],
       "type": "string",
       "description": "Only `retrieve` is paid; the rest are free."
      },
      "params": {
       "type": "object",
       "properties": {
        "k": {
         "type": "integer",
         "description": "Max hits to return (1-50, default 10)"
        },
        "base": {
         "type": "string"
        },
        "lang": {
         "type": "string"
        },
        "mode": {
         "enum": [
          "sparse"
         ],
         "type": "string",
         "description": "Only `sparse` is advertised; dense/hybrid return -32005"
        },
        "page": {
         "type": "string"
        },
        "repo": {
         "type": "string"
        },
        "limit": {
         "type": "string"
        },
        "place": {
         "type": "string"
        },
        "query": {
         "type": "string",
         "description": "Natural-language query, e.g. 'btc price', 'weather in Berlin', 'nba scores', 'commits cloudflare/workers-sdk', 'hacker news top stories', 'what is Base blockchain'"
        },
        "story": {
         "type": "string"
        },
        "league": {
         "type": "string"
        },
        "quotes": {
         "type": "string"
        },
        "symbol": {
         "type": "string"
        },
        "collection": {
         "enum": [
          "crypto",
          "weather",
          "github",
          "sports",
          "fx",
          "hn",
          "wiki",
          "stocks",
          "news",
          "geo",
          "npm",
          "pypi",
          "hnsearch",
          "ens"
         ],
         "type": "string",
         "description": "Skip query parsing and target a collection directly"
        }
       }
      },
      "jsonrpc": {
       "type": "string",
       "const": "2.0"
      }
     }
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     
… (truncated)
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "id": 1,
  "result": {
   "hits": [
    {
     "id": "crypto:BTC",
     "meta": {
      "kind": "crypto.price",
      "symbol": "BTC",
      "priceUsd": 84621.74
     },
     "text": "Bitcoin (BTC) is trading at $84,621.74 USD, 24h +1.83%. Source: Binance BTCUSDT.",
     "score": 1,
     "citation": {
      "uri": "https://www.binance.com/en/trade/BTCUSDT",
      "title": "Bitcoin price"
     }
    }
   ],
   "_meta": {
    "query": "what is the btc price",
    "returned": 1,
    "routedBy": "query-parse",
    "upstream": "api.binance.com / api.coinbase.com",
    "fromCache": false,
    "collection": "crypto",
    "freshnessSeconds": 30,
    "routingConfidence": 0.9
   }
  },
  "jsonrpc": "2.0"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/sentinel402-rcp-1-retrieval-server-a757c695/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from pii-guardrail.chronokey.workers.dev](https://www.zero.xyz/host/pii-guardrail.chronokey.workers.dev/llms.txt)