# agent402.tools Schema Evolution Drift Check

> agent402.tools Schema Evolution Drift Check is a paid API for AI agents from agent402.tools, paid per call via x402, $0.008/call, status unknown (last checked 2026-09-14).

Diffs two OpenAPI snapshots to detect breaking changes, lint agent-readiness regressions, and extract a structured evolution report for integration maintenance.

## Facts

- Endpoint: POST https://agent402.tools/api/skill/schema-evolution
- Price: $0.008/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent402-tools-schema-evolution-drift-check-0b621797
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_12f_8t5jgOhmdbQuyqkij

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 agent402-tools-schema-evolution-drift-check-0b621797 -d '<json body>'
```

Example prompt: Can you check whether our API integration is broken by the latest spec update? Here's the old OpenAPI snapshot and the new one — diff them structurally, flag any breaking changes, and lint the new version for agent-readiness regressions.

## When to prefer this

Choose this endpoint when you need a bundled, single-call workflow that combines structural diffing, breaking change detection, AND agent-readiness linting in one step. Prefer it over a manual multi-step pipeline when you want a holistic API contract drift report without orchestrating separate tools.

## Known failure modes

- Invalid or unparseable YAML/JSON in either spec field — returns parse error
- Missing oldSpec or newSpec — returns validation error for required fields
- Specs that are too large to process within timeout — may return timeout or truncation error
- Non-OpenAPI documents submitted as specs — may return schema mismatch or empty diff

## How this service works

Bundled execution of the API contract drift check workflow - The 'did this API contract change in a way that breaks our integration?' workflow. Diff two OpenAPI snapshots structurally, lint the new one for agent-readiness regressions, extract the endpoint surface for inventory comparison, validate a known-good payload against the new contract, and summarize security-relevant changes. Six tools, one go/no-go answer on whether the upstream API broke us.

## Output

Returns a structured report that includes: a structural diff between the two OpenAPI snapshots highlighting added, removed, and modified endpoints or schemas; a list of breaking changes that could break existing integrations; and lint findings on agent-readiness regressions in the new spec.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "newSpec": {
   "type": "string",
   "description": "the current OpenAPI snapshot as a JSON document (object or JSON string)"
  },
  "oldSpec": {
   "type": "string",
   "description": "the prior OpenAPI snapshot as a JSON document (object or JSON string)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "args": {
   "newSpec": "{\"openapi\":\"3.0.3\",\"info\":{\"title\":\"Orders API\",\"version\":\"1.1.0\"},\"paths\":{\"/v1/orders\":{\"post\":{\"operationId\":\"createOrder\",\"requestBody\":{\"required\":true,\"content\":{\"application/json\":{\"schema\":{\"type\":\"object\",\"required\":[\"customerId\",\"currency\"],\"properties\":{\"customerId\":{\"type\":\"string\"},\"currency\":{\"type\":\"string\"}}}}}},\"responses\":{\"201\":{\"description\":\"created\"}}}}}}",
   "oldSpec": "{\"openapi\":\"3.0.3\",\"info\":{\"title\":\"Orders API\",\"version\":\"1.0.0\"},\"paths\":{\"/v1/orders\":{\"post\":{\"operationId\":\"createOrder\",\"requestBody\":{\"required\":true,\"content\":{\"application/json\":{\"schema\":{\"type\":\"object\",\"required\":[\"customerId\"],\"properties\":{\"customerId\":{\"type\":\"string\"},\"currency\":{\"type\":\"string\"}}}}}},\"responses\":{\"201\":{\"description\":\"created\"}}}}}}"
  },
  "pack": "schema-evolution",
  "steps": [
   {
    "ok": true,
    "slug": "openapi-diff",
    "result": {}
   },
   {
    "ok": true,
    "slug": "openapi-lint",
    "result": {}
   },
   {
    "ok": true,
    "slug": "openapi-extract",
    "result": {}
   },
   {
    "ok": true,
    "slug": "openapi-required-params",
    "result": {}
   },
   {
    "ok": true,
    "slug": "openapi-validate-payload",
    "result": {}
   },
   {
    "ok": true,
    "slug": "openapi-security-summary",
    "result": {}
   }
  ],
  "summary": "6/6 steps succeeded"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent402-tools-schema-evolution-drift-check-0b621797/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent402.tools](https://www.zero.xyz/host/agent402.tools/llms.txt)