# Screenshot Evidence Check

> Screenshot Evidence Check is a paid API for AI agents from api.aiskills402.com, paid per call via x402, $0.03/call, status unknown (last checked 2026-10-27).

Analyzes a description of how a web page was captured or measured and returns a JSON verdict on what that evidence proves, what it cannot prove, and the single measurement that would be decisive.

## Facts

- Endpoint: GET https://api.aiskills402.com/v1/skills/screenshot-evidence-check/file?utm_source=zero.xyz
- Price: $0.03/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-27
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/screenshot-evidence-check-f7ec3598
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_v-tWQyrilTl6OP9Jutdoj

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 screenshot-evidence-check-f7ec3598
```

Example prompt: I captured our landing page using a headless browser at 1280x800 window size and took a full-page tall screenshot — can you tell me what that actually proves about the page layout, what it can't prove, and what single measurement would settle the question?

## When to prefer this

Choose this endpoint when an AI agent or QA engineer needs to reason about the validity and limitations of a specific web page capture or performance measurement — especially when the capture method introduces biases or blind spots (headless browser, tall screenshot, automation session age, OS-specific tools). Prefer over generic QA or performance APIs when the goal is epistemological: not what the page looks like, but what the evidence proves.

## Known failure modes

- Ambiguous or vague capture description may produce an inconclusive verdict
- Descriptions of unsupported or unknown measurement tools may result in a generic analysis
- Missing key parameters (e.g. window size or tool name) may reduce verdict accuracy
- Payment failure via x402 returns 402 status and no content

## How this service works

Screenshot Evidence Check — Reads a description of how a web page was captured or measured - a headless browser capture with a window size, a tall screenshot, a document width reading, a local Lighthouse run, a PageSpeed Insights run, an automation session that has been open for hours, a command-line download size on Windows - and says what that evidence proves, what it cannot prove and the one measurement that would decide, answered as JSON with a verdict. Knows the ways the capture itself pro…

## Output

A JSON object containing a verdict field, a description of what the described capture method proves, what it cannot prove, and the single most decisive follow-up measurement that would resolve remaining uncertainty about the web page capture or measurement.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET",
      "HEAD"
     ],
     "type": "string"
    },
    "headers": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "file": {
   "name": "SKILL.md",
   "content": "<the SKILL.md file>",
   "encoding": "utf-8"
  },
  "name": "Screenshot Evidence Check",
  "skill": "screenshot-evidence-check",
  "sha256": "<sha256 of SKILL.md>",
  "receipt": {
   "tx": "0x<settlement transaction>",
   "settled": true
  },
  "version": "1.0.0",
  "redownload": {
   "url": "<api>/v1/purchases/<token>",
   "token": "<64 hex chars>"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/screenshot-evidence-check-f7ec3598/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.aiskills402.com](https://www.zero.xyz/host/api.aiskills402.com/llms.txt)