# SALT19 Agent Claim Output Verifier

> SALT19 Agent Claim Output Verifier is a paid API for AI agents from api.salt19.com, paid per call via x402, $0.45/call, status unknown (last checked 2026-09-15).

Verifies whether an agent-generated claim is supported, partially supported, or contradicted by a given set of evidence, returning a structured verdict with confidence score and breakdown.

## Facts

- Endpoint: POST https://api.salt19.com/v1/agent-claim-output-verifier
- Price: $0.45/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/salt19-agent-claim-output-verifier-07a6bd18
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_VS3k9X8jH3xIikkPslnTh

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 salt19-agent-claim-output-verifier-07a6bd18 -d '<json body>'
```

Example prompt: Check whether the claim 'the deployment is healthy and payment reconciliation succeeded' is supported by this evidence — logs showing healthy pods but no payment confirmation records — using a 'preponderance of evidence' standard, and tell me what's supported, what's contradicted, and what evidence is missing.

## When to prefer this

Choose this endpoint when an AI agent needs to audit or sanction its own outputs or another agent's claims before acting on them — especially in governed, high-stakes, or multi-step agentic workflows where unverified assertions could cause errors downstream. Particularly useful when structured evidence items with source attribution and temporal metadata are available, and when a specific evidentiary standard (e.g. preponderance, clear and convincing) should be applied. Prefer this over general LLM fact-checking when you need a structured verdict with confidence scores and a broken-down analysis of supported vs. unsupported claim elements.

## Known failure modes

- Claim text or evidence items exceed maximum character limits, causing validation error
- Evidence array exceeds 64 items limit
- Missing required 'claim' field returns 400 error
- Ambiguous or vague claims may result in low-confidence PARTIALLY_SUPPORTED verdicts with broad missing_evidence lists
- Required standard field not interpretable may result in generic evaluation criteria being applied
- Payment of 0.5 USDC not completed causes 402 Payment Required response

## How this service works

SALT19 is an independent applied AI systems lab behind EvoMind governed cognition, the MCP-native Agent Utility Grid, the ARCS research community, AeroClear UAS flight intelligence, and practical software for real-world work.

## Output

A JSON object containing: a verdict string (e.g. SUPPORTED, PARTIALLY_SUPPORTED, CONTRADICTED, UNSUPPORTED), a confidence score between 0 and 1, a list of contradictions found in the evidence, a list of missing evidence items needed to fully support the claim, a list of supported claim elements, and a list of unsupported claim elements.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "claim": {
   "type": "string",
   "maxLength": 12000,
   "minLength": 1
  },
  "context": {
   "type": "string",
   "maxLength": 8000
  },
  "evidence": {
   "type": "array",
   "items": {
    "oneOf": [
     {
      "type": "string",
      "maxLength": 8000,
      "minLength": 1
     },
     {
      "type": "object",
      "required": [
       "statement"
      ],
      "properties": {
       "id": {
        "type": "string",
        "maxLength": 256
       },
       "source": {
        "type": "string",
        "maxLength": 1000
       },
       "relation": {
        "enum": [
         "SUPPORTS",
         "CONTRADICTS",
         "NEUTRAL"
        ],
        "type": "string"
       },
       "statement": {
        "type": "string",
        "maxLength": 8000,
        "minLength": 1
       },
       "observed_at": {
        "type": "string",
        "maxLength": 128
       }
      },
      "additionalProperties": false
     }
    ]
   },
   "maxItems": 64
  },
  "required_standard": {
   "type": "string",
   "maxLength": 2000
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "verdict": "PARTIALLY_SUPPORTED",
  "confidence": 0.5,
  "contradictions": [],
  "missing_evidence": [
   "Independent evidence supporting or contradicting: payment reconciliation succeeded"
  ],
  "supported_elements": [
   "The deployment is healthy"
  ],
  "unsupported_elements": [
   "payment reconciliation succeeded"
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/salt19-agent-claim-output-verifier-07a6bd18/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.salt19.com](https://www.zero.xyz/host/api.salt19.com/llms.txt)