API reference · Posts

Preview or atomically create a scheduled calendar

POST /v1/posts/calendar

Validate 1 to 200 scheduled posts as a batch. Preview with dryRun=true, then apply with the returned snapshot and a unique idempotencyKey. Either every post and the receipt are stored or none are. A cadence may assign UTC instants from startAt and everyMinutes; omit it to give each post its own scheduledAt. Credits are charged when posts publish, not when the calendar is created. Timer arming is best-effort, with the due-post runner as a backstop.

Request

Authenticate with a bearer API key. Agents calling over MCP authorise with OAuth instead and never handle the key.

curl -X POST https://api.postlake.dev/v1/posts/calendar \
  -H "Authorization: Bearer $POSTLAKE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"posts":[{"text":"Launch video","accounts":["acc_123"],"scheduledAt":"2026-10-01T09:00:00Z"}],"dryRun":true}'

Body

FieldTypeRequiredWhat it is
postsarray of objectYesNormal POST /v1/posts bodies with a future scheduledAt, unless cadence assigns the times. Drafts and partial destinations are not accepted.
cadenceobjectNo
cadence.startAtstringYesTimezone-qualified start instant.
cadence.everyMinutesintegerYesElapsed minutes between consecutive posts.
dryRunbooleanYes
snapshotstringNoRequired for apply; return value from preview.
idempotencyKeystringNoRequired for apply; 8 to 128 letters, digits, underscores or hyphens.

Response

Preview with exact UTC slots and snapshot. (200).

FieldTypeRequiredWhat it is
dryRunbooleanNo
snapshotstringNo
matchedintegerNo
resultsarray of objectNo

Example

{
  "dryRun": false,
  "snapshot": "…",
  "matched": 0,
  "results": [
    {}
  ]
}

What it costs

One credit per network the post actually reaches. X uses dedicated rates: 8 credits for text and 90 for a post with a link. Nothing is charged for a target that fails, and a post refused by pre-flight never touches the ledger at all.

Publishing endpoints are limited to 60 requests a minute per account, inside a wider ceiling of 600 a minute across the whole API. Every response carries X-RateLimit-Remaining and X-RateLimit-Reset.

Calling this from an agent

Agents do not call REST. They call tools. Over the hosted MCP server this operation is create_scheduled_calendar, and the agent authorises with OAuth so your API key is never pasted into a chat or seen by the model. The reply comes back in the same normalised shape you see above, which is what lets an agent reason about it without a per-network branch.

You control what any one agent may do with it: which brands it may act for, which networks it may reach, how much it may do in a day, and whether it may spend credits you bought up front. See the MCP server.

Errors

Every failure uses one shape: a stable type, a granular code, the field at fault in param, and a plain-language fix. An agent can act on it without a person reading the message. See Errors and retries.

Check the result before retrying a write. Only operations that explicitly support idempotency can safely replay an Idempotency-Key.

Common questions

Can an AI agent do this without the REST API?

Yes. Over MCP the same job is the create_scheduled_calendar tool. The agent authorises with OAuth, so no API key is pasted into a chat or seen by the model, and the answer comes back in the same normalised shape.

Is it safe to retry this call?

Do not automatically repeat a write after a timeout unless that endpoint explicitly documents idempotency. First read the resulting state; a second request could repeat the action.

What happens when it fails?

You get one error shape: a stable type, a granular code you can branch on, the offending field in param, and a fix written so an agent can correct itself rather than stop. Full list on Errors and retries.

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