# magent FAST Four-Window Calculator

> magent FAST Four-Window Calculator is a paid API for AI agents from api.magentlab.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-14).

Computes a FAST exam aggregate result (Scalea 1999 four Ps) from four caller-assigned boolean window findings: perihepatic, perisplenic, pelvic, and pericardial.

## Facts

- Endpoint: GET https://api.magentlab.com/api/calc/fast
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/magent-fast-four-window-calculator-349b9646
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_e-46jNHevEY__K9wNMSDR

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 magent-fast-four-window-calculator-349b9646
```

Example prompt: The trauma patient's FAST exam shows Morison's pouch positive for free fluid, perisplenic negative, pelvic negative, and pericardial negative — is the overall FAST positive?

## When to prefer this

Use this endpoint when you need a deterministic, rule-based aggregation of Scalea 1999 FAST four-Ps window findings into a single positive/negative result. It is ideal for clinical workflows or agentic pipelines that already have the four boolean window findings and need a consistent, auditable computation rather than any AI interpretation of imaging. Prefer it over general-purpose LLM reasoning when you need strict adherence to the published FAST protocol with no ambiguity.

## Known failure modes

- Missing required query parameter (perihepatic, perisplenic, pelvic, or pericardial) returns a validation error
- Non-boolean value passed for any window parameter causes a schema rejection
- Payment not provided or invalid results in HTTP 402 response
- Caller misclassifies ultrasound findings before passing them — the endpoint cannot detect or correct interpretation errors

## How this service works

Scalea 1999 FAST four Ps (pericardial, perihepatic, perisplenic, pelvic). Each window is a caller-assigned boolean for free intraperitoneal fluid (perihepatic/Morison, perisplenic, pelvic) or pericardial fluid. positive is true if any window is positive and false only if all four are negative. Sequence is not required. Not eFAST pleural views. Not Huang or McKenney scoring. Not a laparotomy order. magent does not scan or interpret ultrasound. Not a medical device.

## Output

Returns a JSON object containing a 'positive' boolean that is true if any of the four FAST windows (perihepatic, perisplenic, pelvic, pericardial) was passed as true, and false only if all four were passed as false. No imaging interpretation is performed; the caller supplies all window findings.

## 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": [
      "perihepatic",
      "perisplenic",
      "pelvic",
      "pericardial"
     ],
     "properties": {
      "pelvic": {
       "type": "boolean",
       "description": "Pelvic window positive for free intraperitoneal fluid as assigned by the caller (Scalea 1999 four Ps). true or false. magent does not interpret ultrasound."
      },
      "pericardial": {
       "type": "boolean",
       "description": "Pericardial window positive for pericardial fluid as assigned by the caller (Scalea 1999 four Ps). true or false. magent does not interpret ultrasound."
      },
      "perihepatic": {
       "type": "boolean",
       "description": "Perihepatic (Morison / right-upper-quadrant) window positive for free intraperitoneal fluid as assigned by the caller (Scalea 1999 four Ps). true or false. magent does not interpret ultrasound."
      },
      "perisplenic": {
       "type": "boolean",
       "description": "Perisplenic (left-upper-quadrant) window positive for free intraperitoneal fluid as assigned by the caller (Scalea 1999 four Ps). true or false. magent does not interpret ultrasound."
      }
     }
    }
   },
   "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/magent-fast-four-window-calculator-349b9646/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)