# Council of AI Coverage Evidence API

> Council of AI Coverage Evidence API is a paid API for AI agents from councilof.ai, paid per call via x402, $0.02/call, status unknown (last checked 2026-11-02).

Returns a signed cryptographic measurement artifact for an AI system, including a SHA-256 content address and Ed25519 attestation signature, verifiable against the public CSOAI ledger.

## Facts

- Endpoint: POST https://councilof.ai/api/coverage-evidence?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/council-of-ai-coverage-evidence-api-fa12769b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_QFQPQ2bBwQBNs39vOVal-

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 council-of-ai-coverage-evidence-api-fa12769b -d '<json body>'
```

Example prompt: Can you fetch the signed coverage evidence artifact from Council of AI for our AI system right now, so I can check the SHA-256 hash and Ed25519 attestation and verify it against their public ledger?

## When to prefer this

Choose this endpoint when you need a tamper-evident, cryptographically signed measurement artifact for an AI system from an independent UK measurement body. It is uniquely suited for compliance workflows, supplier audits, procurement due diligence, or transparency reporting where verifiable third-party attestation (not a self-reported score or badge) is required. Prefer this over AI benchmarks or leaderboards when you need a public, re-checkable evidence artifact with a cryptographic hash rather than a numeric grade or ranking.

## Known failure modes

- Missing or malformed required input fields returns a validation error
- Payment not received or x402 protocol failure results in 402 Payment Required
- Ed25519 key not yet provisioned results in sig_ed25519 being null with an unsigned_reason explanation
- No measurement data available for the requested subject returns an empty or partial artifact
- Network timeout or service unavailability returns a 5xx error

## How this service works

UK AI measurement infrastructure operated by CSOAI Ltd. Read current measurements, verify signed evidence for free and inspect the public corrections ledger.

## Output

Returns a JSON object containing a measurement artifact with a SHA-256 content address, an Ed25519 signature (signed under did:web:csoai.org#board-attestation-1 when the key is provisioned, otherwise null with an unsigned_reason field), a list of unmeasured items, the artifact schema identifier, a verification URL (https://councilof.ai/gspc-verify), and a human-readable note clarifying the artifact is a measurement record and not a grade, rank, score, or certificate.

## 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",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "properties": {},
     "additionalProperties": false
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST",
      "PUT",
      "PATCH"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {},
     "additionalProperties": false
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "required": [
      "schema",
      "artifact",
      "note"
     ],
     "properties": {
      "note": {
       "type": "string"
      },
      "schema": {
       "type": "string"
      },
      "verify": {
       "type": "string"
      },
      "artifact": {
       "type": "object"
      }
     }
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "note": "Measurement artefact — never a grade, rank, score, or certificate.",
  "schema": "<the door's csoai artifact schema>",
  "verify": "https://councilof.ai/gspc-verify",
  "artifact": {
   "sha256": "<64-hex content address>",
   "unmeasured": [],
   "sig_ed25519": "<Ed25519 under did:web:csoai.org#board-attestation-1 when the Pages key is provisioned, else null with unsigned_reason>"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/council-of-ai-coverage-evidence-api-fa12769b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from councilof.ai](https://www.zero.xyz/host/councilof.ai/llms.txt)