WritersLogic Verifiable AI Agent Hub Unit Convert API
The Unit Convert API from WritersLogic Verifiable AI Agent Hub — 1 operation(s) for unit convert.
Work with this as data
Every API here is available over the APIs.io API and to AI agents over MCP.
MCP server
One button, every client — Claude, Cursor, VS Code and the rest.
https://apis.io/mcp
Tools for apis
7 MCP tools reach this
find_apisBrowse and filter every API in the catalog.get_api_artifactsOne API's artifacts, grouped by type.get_openapiThe primary OpenAPI for this API.find_similar_apisAPIs that look like this one.apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.resolveTurn a domain, URL or GitHub org into the provider it belongs to.find_cohortsEvery scored population of providers in the catalog.
Call it yourself
curl for this page
This API
curl "https://apis.io/api/v1/apis/writerslogic-com:writerslogic-com-unit-convert-api"
All apis
curl "https://apis.io/api/v1/apis?limit=25"Calls without X-API-Key need no key. Calls with it need a paid plan — get a key.
Get an API key
Free tier, no form to fill in. Signing in shares your email address with us — we store it to create your key and to recognise you if you sign in with another provider. See our Privacy Policy and Terms.
A second provider on the same verified email joins the account you already have.
OpenAPI Specification
openapi: 3.2.0
info:
title: WritersLogic Verifiable AI Agent Hub Unit Convert API
version: 2.0.0
description: Pay-per-call agents settled in USDC on Base via x402. Every response carries a signed provenance envelope.
contact:
name: WritersLogic
url: https://writerslogic.com/agents
email: agents@writerslogic.com
servers:
- url: https://agents.writerslogic.com
tags:
- name: Unit Convert
paths:
/api/v1/unit-convert:
post:
operationId: unit_convert
summary: Exact unit conversion with dimensional analysis (NIST SP 811)
description: 'Converts up to 100 values between units for an agent that needs the exact factor and a refusal when the units do not match: SI and NIST SP 811 length, mass, time, volume, pressure, energy, power, temperature, with compound expressions like kg*m/s^2. Rejects incompatible dimensions, converts absolute temperatures affinely through kelvin and temperature differences linearly, and converts mass to volume (cups to grams) only with a caller-supplied density. It does NOT look up ingredient densities, guess which cup or gallon a bare symbol means (cup is 236.5882365 mL US customary, 240 mL US label, 250 mL metric or 200 mL Japanese: say which), or handle currencies and dates.
Price: 0.005 USDC on Base (x402).'
x-x402-price-usdc: '0.005'
x-x402-amount: '5000'
x-payment-info:
protocols:
- x402
price:
mode: fixed
currency: USD
amount: '0.005'
x-audience: business
x-sample-url: https://agents.writerslogic.com/api/v1/samples/unit-convert
security:
- x402: []
- apiKey: []
requestBody:
required: true
content:
application/json:
schema:
type: object
additionalProperties: false
required:
- items
properties:
items:
type: array
items:
type: object
additionalProperties: false
required:
- value
- from
- to
properties:
value:
anyOf:
- type: number
- type: string
maxLength: 50
pattern: ^-?\d{1,30}(\.\d{1,30})?([eE][+-]?\d{1,3})?$
description: A finite number, or a decimal string when the digits must stay exact ("236.5882365"). Magnitude at most 1e15.
from:
type: string
maxLength: 80
description: 'Unit expression: symbols, SI prefixes, * / ^ and parentheses, e.g. m/s^2, kg*m/s2, degF, cup_us, lb/ft3. Bare cup/tbsp/tsp/gal/pt/qt/floz/cal/hp/ton are ambiguous and answer unknown with the candidates.'
to:
type: string
maxLength: 80
description: Target unit expression.
kind:
type: string
enum:
- absolute
- difference
description: 'absolute (default): a temperature reading, converted affinely through kelvin. difference: a temperature interval, converted linearly.'
density:
type: object
additionalProperties: false
required:
- value
- unit
properties:
value:
type: number
minimum: 1.0e-09
maximum: 1000000000
description: 'Caller-supplied mass per volume. Never looked up: no ingredient density table is shipped.'
unit:
type: string
maxLength: 40
description: Mass per volume unit expression, e.g. g/mL, kg/m3, lb/ft3, oz/cup_us.
description: Per-item density, overriding the top-level one. Required to cross mass and volume (cups to grams).
claimed:
anyOf:
- type: number
- type: string
maxLength: 50
pattern: ^-?\d{1,30}(\.\d{1,30})?([eE][+-]?\d{1,3})?$
description: Optional claimed result in the target unit; a mismatch beyond relTolerance fails with expected vs actual.
relTolerance:
type: number
description: Relative tolerance for claimed. Default 1e-9.
minimum: 0
maximum: 1
label:
type: string
maxLength: 80
description: Free label echoed back.
maxItems: 100
minItems: 1
description: Conversions to run.
density:
type: object
additionalProperties: false
required:
- value
- unit
properties:
value:
type: number
minimum: 1.0e-09
maximum: 1000000000
description: 'Caller-supplied mass per volume. Never looked up: no ingredient density table is shipped.'
unit:
type: string
maxLength: 40
description: Mass per volume unit expression, e.g. g/mL, kg/m3, lb/ft3, oz/cup_us.
description: Default density for items that cross mass and volume.
precision:
type: integer
description: Significant digits of the reported value. Default 12.
minimum: 1
maximum: 30
example:
items:
- value: 212
from: degF
to: degC
- value: 1
from: cup_us
to: mL
- value: 10
from: degC
to: degF
kind: difference
responses:
'200':
description: Paid result with provenance
content:
application/json:
schema:
type: object
properties:
data:
type: object
properties:
status:
type: string
enum:
- pass
- fail
- unknown
- unsupported
description: 'pass: every rule held. fail: a rule was violated (see witnesses). unknown: the input lacks the evidence to decide. unsupported: outside what this engine covers. Missing evidence is never a pass.'
results:
type: array
items:
type: object
properties:
index:
type: integer
label:
type: string
status:
type: string
enum:
- pass
- fail
- unknown
- unsupported
from:
type: string
to:
type: string
kind:
type: string
value:
type: string
description: Converted value rounded to `precision` significant digits, as a plain decimal string.
valueNumber:
type: number
description: Absent when the value exceeds the double range; use value.
exact:
type: boolean
description: True when the unrounded result terminates inside the 60-digit working precision and no inexact factor or density was used.
path:
type: string
sources:
type: array
items:
type: string
note:
type: string
reason:
type: string
description: Rule id when the item did not pass.
message:
type: string
candidates:
type: array
items:
type: string
precision:
type: integer
witnesses:
type: array
items:
type: object
properties:
ruleId:
type: string
detail:
type: string
path:
type: string
description: JSON pointer or dotted path into the input.
offset:
type: integer
index:
type: integer
expected:
description: What the rule required.
actual:
description: What the input had.
versions:
type: object
description: Every semantic dependency of this answer (engine, tables and their as-of dates, tokenizer, calendar, rounding profile).
limits:
type: array
items:
type: string
deterministic:
type: boolean
description: 'Always true: pure code, no model.'
_provenance:
type: object
description: C2PA-aligned manifest and W3C VC 2.0 (eddsa-jcs-2022) issued by the hub DID; verify at POST /api/v1/verify-provenance
required:
- data
- _provenance
'400':
description: Invalid request (no payment consumed)
content:
application/json:
schema:
type: object
properties:
error:
type: string
code:
type: string
'401':
description: Invalid X-API-KEY
content:
application/json:
schema:
type: object
properties:
error:
type: string
code:
type: string
'402':
description: Payment required or invalid
content:
application/json:
schema:
type: object
description: x402 v2 PaymentRequired (also base64 in the PAYMENT-REQUIRED header)
properties:
x402Version:
type: integer
error:
type: string
code:
type: string
resource:
type: object
accepts:
type: array
items:
type: object
extensions:
type: object
'502':
description: Upstream failure; the payment is released or not settled
content:
application/json:
schema:
type: object
properties:
error:
type: string
code:
type: string
tags:
- Unit Convert
components:
securitySchemes:
x402:
type: apiKey
in: header
name: PAYMENT-SIGNATURE
description: x402 v2 payment payload (base64) sent after a 402 challenge
apiKey:
type: apiKey
in: header
name: X-API-KEY