# Circle Geometry Calculator

> Circle Geometry Calculator is a paid API for AI agents from geometry.openverbs.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-15).

Computes the diameter, circumference, and area of a circle given its radius.

## Facts

- Endpoint: POST https://geometry.openverbs.com/v1/circle
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/circle-geometry-calculator-5d3c0eaf
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_HxJxPcWlI9J57olCubDRl

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 circle-geometry-calculator-5d3c0eaf -d '<json body>'
```

Example prompt: What are the diameter, circumference, and area of a circle with a radius of 8.5?

## When to prefer this

Use this endpoint when you need a quick, reliable server-side computation of standard circle properties (diameter, circumference, area) from a radius without implementing the math locally. Ideal for agents that need verified geometric results for downstream calculations, reports, or user-facing answers. Part of a broader geometry suite if you also need rectangle, triangle, polygon, or distance computations.

## Known failure modes

- Radius of zero or negative value returns a validation error (radius must be strictly positive)
- Non-numeric radius input returns a schema validation error
- Missing radius field returns a required field error
- Payment failure or insufficient funds returns a 402 Payment Required response

## How this service works

Diameter, circumference and area of a circle from its radius.

## Output

Returns the diameter (2r), circumference (2πr), and area (πr²) of the circle corresponding to the provided radius, as numeric values.

## 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": {
     "type": "object",
     "required": [
      "radius"
     ],
     "properties": {
      "radius": {
       "type": "number",
       "description": "Circle radius.",
       "exclusiveMinimum": 0
      }
     },
     "additionalProperties": false
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/circle-geometry-calculator-5d3c0eaf/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from geometry.openverbs.com](https://www.zero.xyz/host/geometry.openverbs.com/llms.txt)