# Hermes Schema Drift Detector

> Hermes Schema Drift Detector is a paid API for AI agents from hermes-counterparty-api.onrender.com, paid per call via x402, $0.015/call, status unknown (last checked 2026-09-15).

Compares two JSON or CSV datasets (current vs baseline) to detect schema drift — added, removed, type-changed, or nullable-changed fields — and flags breaking changes.

## Facts

- Endpoint: POST https://hermes-counterparty-api.onrender.com/v1/schema-drift
- Price: $0.015/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/hermes-schema-drift-detector-344022cf
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__jb52Nkes9D-3-fNx6wVp

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 hermes-schema-drift-detector-344022cf -d '<json body>'
```

Example prompt: Compare these two JSON datasets and tell me if the schema has drifted — specifically whether any fields were added or removed, if any types changed, and whether there's a breaking change: baseline has records [{"id":1,"name":"Alice"}] and current has records [{"id":1,"name":"Alice","email":"a@b.com"}].

## When to prefer this

Choose this endpoint when you need a deterministic, structured diff of two JSON or CSV schemas — especially when you require a breaking-change flag and field-level fingerprints for audit or alerting. Prefer it over manual diffing or general-purpose LLM comparison when you need a reliable, repeatable schema fingerprint and a machine-readable breakdown of exactly which fields changed and how.

## Known failure modes

- Mismatched format field (e.g. sending 'csv' format key but supplying JSON records) returns a validation error
- Empty records array may produce trivially all-removed or all-added field lists
- Extremely large datasets may time out on the Render-hosted free tier
- Missing required 'format' or 'records'/'data' fields returns a schema validation error
- CSV parsing errors if the data string is malformed

## How this service works

Agent utilities for company research, package maintenance intelligence, dependency vulnerability checks, counterparty availability, SEC company snapshots, OFAC sanctions screening, and deterministic JSON/CSV data-quality work. Company domain intelligence includes a free preview before the paid enrichment call.

## Output

Returns a JSON object listing added_fields, removed_fields, type_changes, and nullable_changes arrays, a boolean breaking_change flag, a schema_version string, and SHA-256 fingerprints for both the current and baseline datasets.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "current": {
   "oneOf": [
    {
     "type": "object",
     "required": [
      "format",
      "records"
     ],
     "properties": {
      "format": {
       "type": "string",
       "const": "json"
      },
      "records": {
       "type": "array",
       "items": {
        "type": "object"
       }
      }
     }
    },
    {
     "type": "object",
     "required": [
      "format",
      "data"
     ],
     "properties": {
      "data": {
       "type": "string"
      },
      "format": {
       "type": "string",
       "const": "csv"
      }
     }
    }
   ]
  },
  "baseline": {
   "oneOf": [
    {
     "type": "object",
     "required": [
      "format",
      "records"
     ],
     "properties": {
      "format": {
       "type": "string",
       "const": "json"
      },
      "records": {
       "type": "array",
       "items": {
        "type": "object"
       }
      }
     }
    },
    {
     "type": "object",
     "required": [
      "format",
      "data"
     ],
     "properties": {
      "data": {
       "type": "string"
      },
      "format": {
       "type": "string",
       "const": "csv"
      }
     }
    }
   ]
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "added_fields": [
   "name"
  ],
  "type_changes": [],
  "removed_fields": [],
  "schema_version": "1.0",
  "breaking_change": false,
  "nullable_changes": [],
  "current_fingerprint": "sha256:current",
  "baseline_fingerprint": "sha256:baseline"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/hermes-schema-drift-detector-344022cf/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from hermes-counterparty-api.onrender.com](https://www.zero.xyz/host/hermes-counterparty-api.onrender.com/llms.txt)