# Age Header Validate

> Age Header Validate is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Validates whether an HTTP Age header value fits within a declared freshness lifetime (max-age), returning a deterministic pass/fail finding as versioned JSON.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/age-header-validate
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/age-header-validate-a099c117
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_GXjFm_QnXao6ywunXKrR0

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 age-header-validate-a099c117 -d '<json body>'
```

Example prompt: Check if an HTTP response with an Age header value of '3600' is still fresh given a max-age of 7200 seconds.

## When to prefer this

Choose this endpoint when you need a stateless, deterministic, no-external-dependency check of HTTP Age header freshness against a known max-age value — especially in agentic pipelines that must accept, cache, redirect, or retry web responses and need an auditable pass/fail record. Prefer it over manual arithmetic when you need versioned JSON evidence of the freshness decision.

## Known failure modes

- Missing or invalid 'age' string (non-numeric or empty) may produce an advisory/error status
- Missing 'max_age_seconds' integer causes inability to compute freshness comparison
- Malformed Age header strings (e.g. negative values, non-integer strings) may result in an advisory rather than pass status
- Extremely large integer values for max_age_seconds may be clamped or flagged

## How this service works

Age Header Validate: Age Header Validate checks whether an HTTP Age value fits a declared freshness lifetime from bounded caller-supplied values without an external provider. Call Age Header Validate before accepting, caching, redirecting, or retrying a caller-supplied web response. Returns normalized web evidence, the computed finding, and an explicit pass or advisory status for Age Header Validate as versioned deterministic JSON. Price: $0.001 USDC via x402 on Base. First-party, stateless, me…

## Output

Returns versioned deterministic JSON containing: normalized web evidence (the supplied Age and max-age values), the computed finding (age delta vs freshness limit), and an explicit pass or advisory status indicating whether the HTTP Age value fits within the declared freshness lifetime.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "age": {
   "type": "string",
   "maxLength": 8192,
   "description": "Age supplied to Age Header Validate; used only for this bounded calculation and processed in memory without retention."
  },
  "max_age_seconds": {
   "type": "integer",
   "description": "Max Age Seconds supplied to Age Header Validate; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "age_seconds": 120,
   "within_freshness": true
  },
  "schema": "delx/util-age-header-validate/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "f51799fd712f3514d51db5985cf250b2e699f3081571f017224fd7838e380cc7",
   "external_calls": 0
  },
  "operation": "web_reliability:age_header_validate"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/age-header-validate-a099c117/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)