# Etag Comparison Mode

> Etag Comparison Mode 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).

Compares two HTTP ETags using strong or weak comparison rules and returns a deterministic pass/advisory result with normalized web evidence.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/etag-comparison-mode
- 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/etag-comparison-mode-757a91c9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_AtNeqOJDWcTlZBIBdA4yN

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 etag-comparison-mode-757a91c9 -d '<json body>'
```

Example prompt: Can you do a weak ETag comparison between '"abc123"' and 'W/"abc123"' and tell me if they match?

## When to prefer this

Choose this endpoint when you need a deterministic, stateless, standards-compliant ETag comparison without implementing RFC 7232 comparison logic yourself. Particularly useful in agent workflows that must decide whether to accept, cache, redirect, or retry a web response based on ETag equivalence. Prefer this over ad-hoc string comparison when strong vs weak ETag semantics matter.

## Known failure modes

- Malformed ETag strings (e.g. missing quotes) may result in a validation error or advisory status
- ETags exceeding 8192 characters will be rejected by schema limits
- Invalid or missing required fields return an error response
- Ambiguous ETag formats may produce advisory rather than pass status

## How this service works

Etag Comparison Mode: Etag Comparison Mode evaluates strong or weak comparison between two entity tags from bounded caller-supplied values without an external provider. Call Etag Comparison Mode 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 Etag Comparison Mode as versioned deterministic JSON. Price: $0.001 USDC via x402 on Base. First-party, stateless, memory…

## Output

Returns a versioned deterministic JSON object containing the normalized representation of both input ETags, the computed comparison finding (match or no-match), and an explicit pass or advisory status indicating whether the ETags are considered equivalent under the requested comparison mode.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "left": {
   "type": "string",
   "maxLength": 8192,
   "description": "Left supplied to Etag Comparison Mode; used only for this bounded calculation and processed in memory without retention."
  },
  "weak": {
   "type": "boolean",
   "description": "Weak supplied to Etag Comparison Mode; used only for this bounded calculation and processed in memory without retention."
  },
  "right": {
   "type": "string",
   "maxLength": 8192,
   "description": "Right supplied to Etag Comparison Mode; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "matched": true,
   "left_weak": false,
   "comparison": "weak",
   "right_weak": true
  },
  "schema": "delx/util-etag-comparison-mode/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "43d7a0184e6bebe0515b0b8fc44fcb3a02fe3b3f6fd7bd1f08d1d525deeda0a5",
   "external_calls": 0
  },
  "operation": "web_reliability:etag_comparison_mode"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/etag-comparison-mode-757a91c9/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)