# SignalHarness NFT URI Template Expander

> SignalHarness NFT URI Template Expander is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-16).

Expands NFT URI templates by substituting variables to produce fully resolved NFT metadata URIs.

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/nft_uri_template_expand/invoke
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signalharness-nft-uri-template-expander-397f7703
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_g7gijuINZiCXCWFuotJhh

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 signalharness-nft-uri-template-expander-397f7703 -d '<json body>'
```

Example prompt: Can you expand this NFT URI template for me so I get the actual metadata URL for token 42: 'ipfs://QmExampleHash/{id}.json'?

## When to prefer this

Choose this endpoint when you need to programmatically resolve NFT URI templates into concrete, usable metadata URLs — especially for ERC-721 or ERC-1155 tokens where the URI contains placeholder variables like {id}. It is ideal for NFT marketplaces, wallets, or indexers that need to resolve token metadata URIs on the fly. At $0.005 USDC per call it is cost-effective for per-token resolution needs.

## Known failure modes

- Invalid or malformed URI template string returns an error
- Template variables that cannot be resolved may generate warnings in the response
- Input string exceeding 65536 characters is rejected
- Input shorter than 2 characters is rejected
- Malformed JSON in the request body returns a parse error
- Network or service unavailability returns a non-200 response

## How this service works

Explore 330 pay-per-call x402 API services and 27 agent-native digital products, with Base USDC pricing, secure Polar checkout, and free discovery.

## Output

Returns the fully expanded NFT URI string with all template variables substituted, along with any warnings about the expansion, the service ID, and an evidence scope indicator confirming the data came from caller-supplied input. Also includes a full execution receipt with payment details, request and execution IDs, latency, and a SHA-256 hash of the result for verification.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "nft_uri_request": {
   "type": "string",
   "maxLength": 65536,
   "minLength": 2
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "replay": false,
  "result": {
   "warnings": [
    "URI expansion does not fetch or validate content."
   ],
   "service_id": "nft_uri_template_expand",
   "evidence_scope": "caller_supplied_data",
   "expanded_nft_uri": "{\"token_id_decimal\":\"1\",\"token_id_hex_64\":\"0000000000000000000000000000000000000000000000000000000000000001\",\"uri\":\"ipfs://example/0000000000000000000000000000000000000000000000000000000000000001\"}"
  },
  "status": "succeeded",
  "receipt": {
   "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
   "usage": [],
   "status": "succeeded",
   "network": "eip155:8453",
   "artifacts": [],
   "endedAtMs": 0,
   "latencyMs": 0,
   "paymentId": "example-payment",
   "receiptId": "example-receipt",
   "requestId": "example-request",
   "serviceId": "nft_uri_template_expand",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "5000",
   "resultSha256": "539229320cad7ff6767b2176ba8c0a94484bbb2c4d9113e3b5d43d39b56c8fa4",
   "serviceVersion": "1.0.0",
   "settlementReference": "0x0000000000000000000000000000000000000000000000000000000000000000"
  },
  "artifacts": [],
  "requestId": "example-request",
  "executionId": "example-execution"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/signalharness-nft-uri-template-expander-397f7703/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from signalharness.ai](https://www.zero.xyz/host/signalharness.ai/llms.txt)