# Prague C&M Barrett's Esophagus Classifier

> Prague C&M Barrett's Esophagus Classifier is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Formats caller-supplied circumferential and maximal Barrett's mucosa extents into a standardized Prague C&M notation string (e.g. C2M5).

## Facts

- Endpoint: GET https://api.magentlab.com/api/calc/prague
- 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/prague-c-m-barrett-s-esophagus-classifier-f1de982b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_QVy889kz4JlmEhzBuHkRQ

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 prague-c-m-barrett-s-esophagus-classifier-f1de982b
```

Example prompt: During an endoscopy report, I documented circumferential Barrett's mucosa extending 3 cm above the gastroesophageal junction and maximal extent of 6 cm — can you give me the Prague C&M classification string for those findings?

## When to prefer this

Use this endpoint when you need to encode Barrett's esophagus endoscopic measurements into the internationally standardized Prague C&M notation string per Sharma 2006 consensus criteria. Prefer this over manual formatting to ensure correct validation (M ≥ C constraint, 0–20 cm range). Not appropriate for Los Angeles esophagitis grading, Barrett's diagnosis, or any situation where actual endoscopy or histologic interpretation is needed.

## Known failure modes

- m_cm less than c_cm — invalid input, M must be ≥ C
- c_cm or m_cm outside 0–20 integer range — out of bounds error
- missing required query parameters c_cm or m_cm — 400 bad request
- non-integer values for c_cm or m_cm — schema validation error
- network/payment failure (x402 payment required or insufficient funds)

## How this service works

Sharma 2006 Prague C and M. Caller-assigned circumferential c_cm and maximal m_cm (integers 0-20 cm above the gastroesophageal junction). Returns C{c}M{m} (for example C2M5). M must be ≥ C. C=0 is tongues only (no circumferential Barrett). Not a Barrett diagnosis; histology is required. Not Los Angeles oesophagitis grading. magent does not perform endoscopy. Not a medical device.

## Output

A single Prague C&M notation string (e.g. 'C2M5') encoding the caller-supplied circumferential (C) and maximal (M) Barrett's mucosa extents. The format follows Sharma 2006 Prague consensus criteria. No diagnosis is made; histology confirmation is still required.

## 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",
      "HEAD",
      "DELETE"
     ],
     "type": "string"
    },
    "headers": {
     "type": "object",
     "additionalProperties": {
      "type": "string"
     }
    },
    "queryParams": {
     "type": "object",
     "required": [
      "c_cm",
      "m_cm"
     ],
     "properties": {
      "c_cm": {
       "type": "integer",
       "description": "Caller-assigned circumferential extent of visualized Barrett mucosa in centimetres above the gastroesophageal junction (integer 0-20). C=0 is allowed (no circumferential Barrett; tongues only). magent does not perform endoscopy."
      },
      "m_cm": {
       "type": "integer",
       "description": "Caller-assigned maximal extent of visualized Barrett mucosa in centimetres above the gastroesophageal junction (integer 0-20). Must be greater than or equal to c_cm. magent does not perform endoscopy."
      }
     }
    }
   },
   "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/prague-c-m-barrett-s-esophagus-classifier-f1de982b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.magentlab.com](https://www.zero.xyz/host/api.magentlab.com/llms.txt)