# ThoughtProof Verification Check

> ThoughtProof Verification Check is a paid API for AI agents from api.thoughtproof.ai, paid per call via x402, $0.08/call, status unknown (last checked 2026-10-13).

Verifies AI decisions and reasoning claims, returning a verdict of ALLOW, BLOCK, or UNCERTAIN with a confidence score and list of objections

## Facts

- Endpoint: POST https://api.thoughtproof.ai/v1/check?utm_source=zero.xyz
- Price: $0.08/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/thoughtproof-verification-check-a2a86403
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_KVDw5fZSq9NhR4lp9FwC8

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 thoughtproof-verification-check-a2a86403 -d '<json body>'
```

Example prompt: Before you send that trade order, run a deep ThoughtProof verification check on this reasoning: 'The market is oversold and RSI is below 30, so buying now is low-risk' — I want a ALLOW/BLOCK verdict and any objections it finds.

## When to prefer this

Use this endpoint when an AI agent needs a structured, third-party safety gate on its own decisions or reasoning before taking action — especially in high-stakes autonomous pipelines. Prefer it over simple rule-based filters when you need a calibrated confidence score plus enumerated objections, or when you need per-agent verification history via agentId. Choose 'fast' speed for low-latency pipelines and 'deep' for critical decisions requiring thorough scrutiny.

## Known failure modes

- Missing required 'claim' field returns 400 Bad Request
- Invalid 'speed' value not matching fast/standard/deep returns 400
- Payment not included or insufficient USDC via x402 returns 402 Payment Required
- Claim too long or malformed returns 422 Unprocessable Entity
- Service timeout on deep verification for extremely complex claims
- Unknown domain value may degrade verification quality without explicit error

## How this service works

ThoughtProof — Verification infrastructure for autonomous AI. Three products: Sentinel, PLV, and Reasoning Verification. Pay per call, no minimums.

## Output

Returns a verdict enum (ALLOW, BLOCK, or UNCERTAIN), a numeric confidence score (0–1), duration in milliseconds, and an array of objection strings explaining any detected flaws or risks in the claim.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "claim"
 ],
 "properties": {
  "claim": {
   "type": "string",
   "description": "The decision or reasoning to verify"
  },
  "speed": {
   "enum": [
    "fast",
    "standard",
    "deep"
   ],
   "type": "string",
   "description": "Verification depth. Pricing: fast=$0.008, standard=$0.02, deep=$0.08 (Base USDC via x402)"
  },
  "domain": {
   "enum": [
    "financial",
    "medical",
    "legal",
    "code",
    "general"
   ],
   "type": "string"
  },
  "agentId": {
   "type": "string",
   "description": "Optional caller/agent identifier for per-agent verification history (also accepted via X-Agent-Id header; body wins). Powers GET /v1/stats/{agentId} and /v1/trustscore/{agentId}."
  },
  "stakeLevel": {
   "enum": [
    "low",
    "medium",
    "high",
    "critical"
   ],
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "verdict": {
   "enum": [
    "ALLOW",
    "BLOCK",
    "UNCERTAIN"
   ],
   "type": "string"
  },
  "confidence": {
   "type": "number",
   "example": 0.82
  },
  "durationMs": {
   "type": "integer"
  },
  "objections": {
   "type": "array",
   "items": {
    "type": "string"
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/thoughtproof-verification-check-a2a86403/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.thoughtproof.ai](https://www.zero.xyz/host/api.thoughtproof.ai/llms.txt)