# Cold Email Grader

> Cold Email Grader is a paid API for AI agents from sigtap-outreach-api.sigtap.workers.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Scores a cold email across 12 dimensions and returns actionable fix suggestions

## Facts

- Endpoint: GET https://sigtap-outreach-api.sigtap.workers.dev/grade
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/cold-email-grader-c8065794
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_o7_YqvLdYvmy7ojSg0QRl

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 cold-email-grader-c8065794
```

Example prompt: Can you grade my cold email and tell me what to fix? Here's the email: 'Hi John, I noticed your company recently raised a Series B — congrats! We help SaaS companies like yours cut churn by 30% in 90 days. Worth a 15-minute call this week?'

## When to prefer this

Choose this endpoint when you need structured, multi-dimensional feedback on a cold email draft before sending — especially when you want specific fixes, not just a pass/fail. Ideal for SDRs, sales teams, and copywriters who want a programmatic quality gate before blasting outreach. Pair with the sibling `template` endpoint to generate an email and then immediately grade it, or with `deliverability` to audit technical sending health alongside content quality.

## Known failure modes

- Missing or empty email input returns an error
- Extremely long email text may be truncated or rejected
- Non-email text submitted may produce irrelevant scores
- Network timeout if the Cloudflare Worker is under load
- Malformed request returns HTTP 4xx

## How this service works

Paid micro-utilities for cold-email outreach agents: domain deliverability audits, cold-email grading, template generation, plus a tools toolbox (hashing, JWT decode, IDs, slugs, JSON, regex, crypto prices, domain age, weather). Paid via x402 (USDC on Base). One signature per call. No keys. FREE CHECK: GET /preview/<paid-path> (same URL with /preview/ prefix) returns a 200 demo sample - verify output shape before paying. PAID CALL: GET the url -> 402 challenge -> sign + retry with X-PAYMENT -> settled on-chain (USDC, Base). Ready-to-paste client: GET /llms.txt section "Pay in one call". Catalog+MCP twin: /llms.txt.

## Output

Returns a structured 12-point cold email score breaking down the email across key quality dimensions (such as subject line, personalization, value proposition, call to action, etc.) along with specific, actionable fix suggestions for each dimension that scored poorly.

## 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",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "example": {
  "grade": "B",
  "score": 82,
  "checks": []
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/cold-email-grader-c8065794/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from sigtap-outreach-api.sigtap.workers.dev](https://www.zero.xyz/host/sigtap-outreach-api.sigtap.workers.dev/llms.txt)