# X402 Discovery Parity Check

> X402 Discovery Parity Check is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-13).

Compares tool-name sets from catalog, OpenAPI, portfolio, and runtime sources to detect mismatches before accepting or paying for an x402 agent delivery.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/x402-discovery-parity-check
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-discovery-parity-check-b14ce473
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_u8fyTlYDXlqffAK3_Kaeo

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 x402-discovery-parity-check-b14ce473 -d '<json body>'
```

Example prompt: Before I accept this x402 agent delivery, run a discovery parity check on these four tool sets — my catalog tools are ['tool_a','tool_b'], OpenAPI tools are ['tool_a','tool_c'], portfolio tools are ['tool_a','tool_b'], and runtime tools are ['tool_a','tool_b','tool_d'] — and tell me if they match or what's mismatched.

## When to prefer this

Use this endpoint when you need a deterministic, in-memory, no-external-provider check of tool-name parity across four specific sources (catalog, OpenAPI, portfolio, runtime) before committing to an x402 payment or accepting an agent delivery. Prefer this over manual comparison or general-purpose validation tools when operating in an x402 agentic payment context where caller-supplied challenge and result metadata need explicit accept/reject decisions.

## Known failure modes

- Input arrays exceed 256 items per set causing rejection
- Tool name strings exceed 8192 character limit per item
- Missing or empty tool set arrays resulting in incomplete comparison
- Ambiguous tool names causing false parity or false mismatch
- Network timeout returning no result for large tool sets

## How this service works

X402 Discovery Parity Check: X402 Discovery Parity Check compares tool-name sets from catalog, OpenAPI, portfolio, and runtime from bounded caller-supplied values without an external provider. Call X402 Discovery Parity Check before paying for or accepting an x402 or agent delivery assembled from caller-supplied challenge and result metadata. Returns contract-specific checks, normalized evidence, mismatch reasons, and an explicit acceptance or rejection status for X402 Discovery Parity Check as…

## Output

Returns an explicit acceptance or rejection status, contract-specific validation checks, normalized evidence of each tool set, and a list of mismatch reasons explaining any discrepancies found between the catalog, OpenAPI, portfolio, and runtime tool-name sets.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "catalog_tools": {
   "type": "array",
   "items": {
    "type": "string",
    "maxLength": 8192
   },
   "maxItems": 256,
   "description": "Catalog Tools supplied to X402 Discovery Parity Check; used only for this bounded calculation and processed in memory without retention."
  },
  "openapi_tools": {
   "type": "array",
   "items": {
    "type": "string",
    "maxLength": 8192
   },
   "maxItems": 256,
   "description": "Openapi Tools supplied to X402 Discovery Parity Check; used only for this bounded calculation and processed in memory without retention."
  },
  "runtime_tools": {
   "type": "array",
   "items": {
    "type": "string",
    "maxLength": 8192
   },
   "maxItems": 256,
   "description": "Runtime Tools supplied to X402 Discovery Parity Check; used only for this bounded calculation and processed in memory without retention."
  },
  "portfolio_tools": {
   "type": "array",
   "items": {
    "type": "string",
    "maxLength": 8192
   },
   "maxItems": 256,
   "description": "Portfolio Tools supplied to X402 Discovery Parity Check; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "counts": {
    "catalog": 2,
    "openapi": 2,
    "runtime": 2,
    "portfolio": 2
   },
   "parity": true,
   "missing": {
    "catalog": [],
    "openapi": [],
    "runtime": [],
    "portfolio": []
   }
  },
  "schema": "delx/util-x402-discovery-parity-check/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "2a4e869067b7be7349f2d8d258047e08b504e1fc708e4bef33d84574262c87f4",
   "external_calls": 0
  },
  "operation": "delivery_contract:x402_discovery_parity_check"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-discovery-parity-check-b14ce473/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)