# SignalHarness Agent Handoff Validate

> SignalHarness Agent Handoff Validate is a paid API for AI agents from signalharness.ai, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-13).

Validates a JSON payload representing an agent handoff request, returning structural analysis, warnings, and a verifiable execution receipt.

## Facts

- Endpoint: POST https://signalharness.ai/api/agent/services/agent_handoff_validate/invoke
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/signalharness-agent-handoff-validate-a224279b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Ltzdt6Qx4jHGxuzN2JRY6

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-agent-handoff-validate-a224279b -d '<json body>'
```

Example prompt: Can you validate this agent handoff JSON for me before I pass control to the next agent? Here's the payload: {"target_agent":"researcher","task":"summarize quarterly earnings","context":{"quarter":"Q1","year":2024}}

## When to prefer this

Choose this endpoint when you need a lightweight, pay-per-call validation of an agent handoff JSON payload before committing to an agent-to-agent delegation in a multi-agent workflow. Useful for pre-flight checks in automated pipelines where structural correctness of handoff instructions is critical and you want an auditable, receipted validation step on Base/USDC infrastructure.

## Known failure modes

- Invalid or non-JSON string in request_json — may return a parsing error or schema violation
- Payload exceeds 65536 character limit — request rejected
- Malformed JSON string shorter than 2 characters — rejected by minLength constraint
- Network or payment settlement failure on Base chain — receipt shows failed status
- Caller-supplied data warnings always included — results are not independently verified by the service

## 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 a JSON object containing a status field ('succeeded' or error), an analysis_json string with structural findings, a list of warnings about the submitted data, an evidence_scope indicator, and a cryptographically verifiable receipt including a SHA-256 result hash, payment ID, request ID, execution ID, network (Base/EIP-155:8453), and USDC amount charged.

## Request schema (JSON Schema)

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

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "replay": false,
  "result": {
   "warnings": [
    "Verify the caller-supplied data before relying on this result."
   ],
   "service_id": "agent_handoff_validate",
   "analysis_json": "{\"example\":\"schema-valid caller-supplied data\"}",
   "evidence_scope": "caller_supplied_data"
  },
  "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": "agent_handoff_validate",
   "executionId": "example-execution",
   "startedAtMs": 0,
   "amountAtomic": "5000",
   "resultSha256": "0e9f17ba3b897ec4c0e4e3459ceefdf795ef8dacd32a191b20209b6c62dc9a7a",
   "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-agent-handoff-validate-a224279b/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)