API & MCP

Everything a person can do on Sizewise Rate Counter, a program or AI agent can do with the same inputs and get the identical result.

HTTP API

POST https://sizewiseratecounter.usefulweb.app/api/v1/calculate – run Sizewise Rate Counter
GET https://sizewiseratecounter.usefulweb.app/api/v1/tool – inputs, output schema, examples
OpenAPI 3.1: /openapi.json · /openapi.yaml
Errors: application/problem+json; 422 includes per-field errors.

Sizewise Rate Counter

Converts a rate between seconds, minutes, hours, days, weeks, months and years, projects it over time, finds when it reaches a target and writes a small self-contained HTML counter (“since you opened this page …”) for your own site.

Inputs of Sizewise Rate Counter
Field	Type	Default	Description
`label`	text	"Light travels"	What is counted
`amount`	number	299792.458	Amount
`per`	select (second, minute, hour, day, week, month, year)	"second"	Per
`unit`	text	"km"	Unit of the amount
`elapsedSeconds`	number	60	Elapsed time
`target`	number	0	Target (optional)
`decimals`	integer	0	Decimals in the counter

Example request

Light to the Moon

curl -X POST https://sizewiseratecounter.usefulweb.app/api/v1/calculate -H 'content-type: application/json' -d '{"label":"Light travels","amount":299792.458,"per":"second","unit":"km","elapsedSeconds":60,"target":384400}'

Every result contains

inputs (normalised, defaults applied), summary, result (validated against the published schema), units, assumptions, sources, warnings, computedAt and links.

MCP (Model Context Protocol)

Streamable HTTP endpoint: https://sizewiseratecounter.usefulweb.app/mcp – protocol revisions 2026-07-28 (stateless) and 2025-11-25 / 2025-06-18 / 2025-03-26 (initialize handshake).
Tools: sizewise_rate_counter
Local stdio connector: node src/mcp-stdio.ts --tool=sizewise-rate-counter

{
  "mcpServers": {
    "sizewise-rate-counter": { "type": "http", "url": "https://sizewiseratecounter.usefulweb.app/mcp" }
  }
}