# Nomos BTC/USD Value API

> Nomos BTC/USD Value API is a paid API for AI agents from base-agent-preflight.bytoken2023.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-14).

Returns the current BTC/USD price along with a risk assessment and flags for a given BTC amount.

## Facts

- Endpoint: GET https://base-agent-preflight.bytoken2023.workers.dev/x402/v1/value/btc-usd
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/nomos-btc-usd-value-api-b796d421
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_cFHPyCTxiKOkxiM1Z9z-a

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 nomos-btc-usd-value-api-b796d421
```

Example prompt: What is the current BTC/USD price and risk assessment for 0.75 BTC using Nomos?

## When to prefer this

Choose this endpoint when you need a pay-per-request BTC/USD price lookup that also returns a structured risk assessment and flags — ideal for agent preflight checks before executing BTC-denominated transactions. Prefer it over generic price APIs when you need risk scoring bundled with the price lookup in a single call on the Base network.

## Known failure modes

- Invalid BTC amount format (must match ^[0-9]+(?:\.[0-9]{1,18})?$) returns a 400 error
- Payment not received or insufficient USDC results in 402 Payment Required
- Network or worker outage may return 503
- Negative or zero amount may be rejected
- Missing or malformed query parameters may return validation errors

## How this service works

Machine-payable service intelligence for discovering, verifying, and monitoring identity, risk, authorization, execution-preflight, and evidence APIs before autonomous agents spend.

## Output

Returns a JSON object containing the Base network identifier (eip155:8453), product name (nomos-value-btc-usd), and an assessment object with risk_level (e.g. 'low'), numeric risk_score, and a flags array indicating any detected risk signals. May also include identity, activity, and provenance sub-objects.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [],
     "properties": {
      "amount": {
       "type": "string",
       "pattern": "^[0-9]+(?:\\.[0-9]{1,18})?$",
       "description": "Optional positive decimal BTC amount. Defaults to 1."
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "network": {
       "type": "string"
      },
      "product": {
       "type": "string"
      },
      "activity": {
       "type": "object"
      },
      "identity": {
       "type": "object"
      },
      "assessment": {
       "type": "object"
      },
      "provenance": {
       "type": "object"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "network": "eip155:8453",
  "product": "nomos-value-btc-usd",
  "assessment": {
   "flags": [],
   "risk_level": "low",
   "risk_score": 0
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/nomos-btc-usd-value-api-b796d421/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from base-agent-preflight.bytoken2023.workers.dev](https://www.zero.xyz/host/base-agent-preflight.bytoken2023.workers.dev/llms.txt)