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Mekler AI Response Contract Checker
x402
Mekler AI Response Contract Checker is a paid API for AI agents from api.mekler.ai, paid per call via x402, $0.05/call, status unknown (last checked 2026-10-27).
Validates a JSON response against a Draft 2020-12 schema, checks timestamp freshness, and optionally assesses claim evidence, returning separate pass/fail/review findings for each check.
Price / call$0.05
Success—
StatusUnknown
How this service works
Check supplied JSON against a bounded Draft 2020-12 schema, declared timestamp freshness and optional claim evidence. Return separate pass/fail/review findings. Evidence assessment is advisory and uses supplied excerpts only; no external fact verification, source authentication or URL retrieval.
Output
Returns an object with an overall verdict (pass/fail/review) and separate status blocks for schema validation (including Draft 2020-12 error list and format assertions checked), freshness (age in seconds, pointer used, and reason), and semantic claim assessment (per-claim findings). Also includes a limitations notice and an observed_at timestamp indicating when the check was run.
Example use cases
Schema-gate before writing to database
“Before I save this API response to my database, validate it against my product schema — Draft 2020-12 — and make sure the record_date field is no more than 600 seconds old. Here's the response: {"record_date":"2026-10-21T12:00:00Z","sku":"ABC-123","qty":5} and the schema requires sku to be a non-empty string and qty to be a positive integer.”
Freshness check on a financial data feed
“I'm getting a price quote feed from a third-party API and I need to make sure the quotes are never staler than 60 seconds. Can you check this response payload against my schema and flag whether the quoted_at timestamp is within 60 seconds of right now?”
Claim evidence audit for AI-generated summaries
“I have an AI-generated summary that makes three factual claims — can you check each claim against the evidence excerpts I've pulled from the source document and tell me which ones pass, fail, or need review? Here are the claim pointers and their supporting text excerpts.”
Technical details
Endpoint
POSThttps://api.mekler.ai/v1/data/responses/check-response-contract?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a single call to simultaneously validate a JSON payload against a Draft 2020-12 schema, assess timestamp freshness, and optionally audit claim evidence from supplied excerpts — all in one structured verdict. Prefer it over generic JSON validators when you need freshness checking combined with schema validation, or when you need per-claim evidence review for AI-generated outputs. It is not a substitute for external fact-checking or source authentication, but it is well-suited for automated quality gates in agentic pipelines where structured pass/fail/review outputs are needed programmatically.
Side effects
- Invalid or unparseable JSON schema returns a schema error block with status 'fail'
- Malformed JSON Pointer for freshness field causes a freshness error response
- Timestamp value at the given pointer is missing or not a valid date-time string, causing freshness check to fail
- Evidence excerpts exceed the 3000-character limit per item, causing a 422 validation error
- More than 4 semantic claim items supplied, rejected with a validation error
- request_id not matching the required 16-64 alphanumeric/underscore/hyphen pattern causes rejection
- No external URL retrieval — claims referencing external sources cannot be fact-checked beyond supplied excerpts
- Schema errors may be capped if error_limit_reached is true, meaning not all violations are enumerated
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| schema | — | |
| response | — | |
| semantic | array | |
| freshness | object | |
| request_id | string |
Output
Schema · Response
{
"type": "json",
"example": {
"schema": {
"draft": "2020-12",
"errors": [],
"status": "pass",
"format_assertions": [
"date-time",
"ipv4",
"ipv6",
"uuid"
],
"error_limit_reached": false
},
"status": "ok",
"verdict": "pass",
"semantic": {
"claims": [],
"method": null,
"status": "not_requested"
},
"freshness": {
"reason": "within_declared_age",
"status": "pass",
"pointer": "/updated_at",
"age_seconds": 60
},
"limitations": [
"Only the requested contract is checked; pass is not proof of truth, source authenticity or suitability for a consequential decision."
],
"observed_at": "2026-10-21T12:01:00Z"
}
}Tags
x402
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