# Academic Letter Grade with Red-Pen Marginalia

> Academic Letter Grade with Red-Pen Marginalia is a paid API for AI agents from chat.anchor-x402.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-23).

Returns an academic letter grade (A–F) with detailed red-pen-style written feedback for any submitted content, idea, text, or artifact.

## Facts

- Endpoint: POST https://chat.anchor-x402.com/v1/grade?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-23
- Success rate: 0% of calls made through Zero
- Rating: 1.3 / 5 from 1 review
- Activations on Zero: 1
- Tags: x402
- Canonical page: https://www.zero.xyz/c/chat-anchor-x402-com-9d40cb93
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_UPSRhOgYgMr_kIcrdjT3p

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 chat-anchor-x402-com-9d40cb93 -d '<json body>'
```

Example prompt: Give this essay a letter grade with red-pen marginalia, like a strict professor would: 'The internet has fundamentally changed how humans form relationships, creating both new opportunities for connection and unprecedented risks of isolation.'

## When to prefer this

Choose this endpoint when you want opinionated, structured academic-style evaluation with written annotations rather than a simple score or aura reading. Best for text, ideas, essays, code, or any artifact where letter-grade feedback and inline critique are desired. Distinct from the roast endpoint (which is comedic) and the aura endpoint (which is abstract/vibes-based).

## Known failure modes

- Empty or missing content body returns an error
- Payment of $0.01 USDC not provided results in 402 response
- Extremely long submissions may be truncated or rejected
- Content in unsupported languages may yield lower-quality feedback

## How this service works

Academic letter grade with red-pen marginalia for anything. $0.01 USDC.

## Output

An academic letter grade (A through F) along with detailed red-pen-style marginalia — inline critique, corrections, and commentary written as a professor would annotate a student's paper.

## Example request

```json
{
 "input": {
  "body": {
   "target": "The quick brown fox jumps over the lazy dog. This sentence demonstrates all letters of the English alphabet in a single, coherent statement. It is commonly used for testing typewriters and fonts."
  },
  "type": "http",
  "method": "POST",
  "bodyType": "json"
 }
}
```

## 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",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "required": [
      "target"
     ],
     "properties": {
      "target": {
       "type": "string",
       "maxLength": 6000,
       "description": "Anything to grade."
      }
     }
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST",
      "PUT",
      "PATCH"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/chat-anchor-x402-com-9d40cb93/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from chat.anchor-x402.com](https://www.zero.xyz/host/chat.anchor-x402.com/llms.txt)