Common free time across participants: intersect availability windows, report who blocks

$0.005 USDC per call · Business, finance and compliance · POST /api/v1/slot-intersect · Id slot-intersect

Intersects up to 20 participants' free windows (up to 200 each, half-open RFC 3339 intervals with Z or offsets, so mixed time zones are fine) into the common slots at least minMinutes long, optionally clipped to a search window; when nothing fits, names the participants whose removal would create a slot. Built for an agent scheduling a meeting from already-fetched availability. It does not read calendars, apply working hours or holidays (use appointment-fit), or pick a slot for you.

What you get

Tz-mixed availability lists are where overlap arithmetic goes wrong; one call returns every common slot.

Call it

Send the JSON body below to https://agents.writerslogic.com/api/v1/slot-intersect. An unpaid request answers 402 with the price and how to pay; a request that fails with a 5xx status is not charged.

curl -i -X POST https://agents.writerslogic.com/api/v1/slot-intersect \
  -H 'content-type: application/json' \
  -d '{"participants":[{"id":"ana","free":[{"start":"2026-11-09T09:00:00-05:00","end":"2026-11-09T12:00:00-05:00"}]},{"id":"ben","free":[{"start":"2026-11-09T15:00:00+01:00","end":"2026-11-09T18:00:00+01:00"}]}],"minMinutes":30}'

Input

Field	Type	Required	Description
`participants`	array<object>; max 20 items	yes
`minMinutes`	integer; 1..10080	no	Minimum slot length; default 1.
`window`	object	no	Only consider this range.

Example request body

{
  "participants": [
    {
      "id": "ana",
      "free": [
        {
          "start": "2026-11-09T09:00:00-05:00",
          "end": "2026-11-09T12:00:00-05:00"
        }
      ]
    },
    {
      "id": "ben",
      "free": [
        {
          "start": "2026-11-09T15:00:00+01:00",
          "end": "2026-11-09T18:00:00+01:00"
        }
      ]
    }
  ],
  "minMinutes": 30
}

Result

The response is { "data": ..., "_provenance": ... }. data carries these fields; _provenance is a signed W3C Verifiable Credential with a C2PA-style manifest, checked free at POST /api/v1/verify-provenance.

Field	Type	Required	Description
`status`	string; one of "pass", "fail", "unknown", "unsupported"	no	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.
`slots`	array<object>	no
`slotCount`	integer	no
`totalMinutes`	integer	no
`blockedBy`	array<object>	no	Participants whose absence from the intersection would yield at least one slot.
`reason`	string	no
`witnesses`	array<object>	no
`versions`	object	no	Every semantic dependency of this answer (engine, tables and their as-of dates, tokenizer, calendar, rounding profile).
`limits`	array<string>	no
`deterministic`	boolean	no	Always true: pure code, no model.

Pay and connect

Available through: x402 (USDC on Base), MCP. MCP clients reach it through the calendar-deadline-kit package.

Machine-readable

This agent as JSON (schemas, example, OpenAPI operation)
Free signed sample response
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