# Dev Reference: Cache-Control Header Explainer

> Dev Reference: Cache-Control Header Explainer is a paid API for AI agents from dev-reference.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).

Parses a Cache-Control header value, explains each directive in plain language, computes freshness durations, and flags conflicts or sensitive data leaks.

## Facts

- Endpoint: GET https://dev-reference.x402tookit.com/cache-control-explain?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/dev-reference-cache-control-header-explainer-b8300bcc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_pmoDtwM-8Sl0l4XJ7apEu

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 dev-reference-cache-control-header-explainer-b8300bcc
```

Example prompt: Can you explain what 'private, no-cache, max-age=0, must-revalidate' means in a Cache-Control response header, compute how long it stays fresh, and flag any conflicts or potential privacy issues?

## When to prefer this

Use this endpoint when you need to programmatically interpret, audit, or debug a Cache-Control header value — especially when checking for security issues like caching sensitive data, detecting directive conflicts, or computing exact freshness lifetimes for both browsers and shared caches like CDNs. Prefer it over general HTTP header explainers when Cache-Control-specific freshness math and conflict detection are needed.

## Known failure modes

- Missing 'value' query parameter returns an error
- Malformed or unrecognized directive combinations may produce partial results with notChecked fields
- Invalid 'kind' enum value (not 'request' or 'response') may cause a validation error
- Empty string value may return a minimal or error response

## How this service works

Parse a Cache-Control value, explain each directive, compute freshness and flag conflicts or leaks.

## Output

Returns a structured breakdown of each Cache-Control directive with its plain-English meaning, a computed browser freshness duration and shared cache freshness duration in seconds, a storage classification, a summary verdict, a list of flags with severity levels and fix suggestions, and a degraded indicator if the header is partially unrecognized. Also includes counts of high and medium severity issues.

## 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"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "value"
     ],
     "properties": {
      "kind": {
       "enum": [
        "response",
        "request"
       ],
       "type": "string",
       "description": "response (default) or request"
      },
      "usage": {
       "enum": [
        "static",
        "personalized",
        "sensitive"
       ],
       "type": "string",
       "description": "Optional hint: static, personalized or sensitive, to check the value against that use"
      },
      "value": {
       "type": "string",
       "description": "The header value, for example public, max-age=3600, no-cache"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "kind": {
       "type": [
        "null",
        "string"
       ]
      },
      "flags": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "object",
        "properties": {
         "fix": {},
         "message": {
          "type": [
           "null",
           "string"
          ]
         },
         "severity": {
          "type": [
           "null",
           "string"
          ]
         },
         "directive": {
          "type": [
           "null",
           "string"
          ]
         }
        }
       }
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ]
      },
      "storage": {
       "type": [
        "null",
        "string"
       ]
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "highCount": 
… (truncated)
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/dev-reference-cache-control-header-explainer-b8300bcc/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from dev-reference.x402tookit.com](https://www.zero.xyz/host/dev-reference.x402tookit.com/llms.txt)