# Obol BTC Block Anomaly Detector – Latest Tip

> Obol BTC Block Anomaly Detector – Latest Tip is a paid API for AI agents from obol-x402.fly.dev, paid per call via x402, $0.01/call, status down (last checked 2026-09-15).

Scans the current Bitcoin blockchain tip block for anomalies including fee-exceeds-subsidy, empty blocks, difficulty retargets, timestamp inversions, long block gaps, and unusual coinbase messages.

## Facts

- Endpoint: GET https://obol-x402.fly.dev/v1/btc/anomaly/latest
- Price: $0.01/call
- Payment: x402
- Status: down
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/obol-btc-block-anomaly-detector-latest-tip-3a990a0f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_cDJIpjb0W8u6X-_FrpflO

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 obol-btc-block-anomaly-detector-latest-tip-3a990a0f
```

Example prompt: Check the latest Bitcoin block for any anomalies — things like empty blocks, fees exceeding the subsidy, difficulty retargets, timestamp inversions, long gaps between blocks, or anything weird in the coinbase message.

## When to prefer this

Use this endpoint when an AI agent needs to autonomously monitor or report on the health and unusual properties of the current Bitcoin blockchain tip without specifying a particular block — ideal for real-time alerting workflows, chain health dashboards, or pre-transaction sanity checks. Prefer over general blockchain explorers when you need a structured, agent-friendly anomaly summary rather than raw block data.

## Known failure modes

- Bitcoin node data temporarily unavailable — service may return 503 or timeout
- Payment validation failure — x402 payment not accepted, returns 402
- Block tip data stale if upstream indexer lags — anomaly flags may reflect a slightly older tip
- Rate limiting if called too frequently without valid payment

## How this service works

Validation-gated Bitcoin block anomaly detector on the current tip height. fee-exceeds-subsidy, empty block, difficulty retarget, timestamp inversion, long block gap, coinbase message — latest block scan for agents. Cryptographically signed (Ed25519) — every response is independently verifiable via /.well-known/obol-pubkey.

## Output

Returns a structured anomaly report for the current Bitcoin chain tip block, including boolean flags for each anomaly type (fee-exceeds-subsidy, empty block, difficulty retarget, timestamp inversion, long block gap) and the raw coinbase message, along with the scanned block height.

## 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"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/obol-btc-block-anomaly-detector-latest-tip-3a990a0f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from obol-x402.fly.dev](https://www.zero.xyz/host/obol-x402.fly.dev/llms.txt)