Arcads MCP out of credits vs Sume 402 insufficient_credits

The Arcads MCP article says that without an active subscription, or after you run out of credits, generation requests will fail. On Sume the failure is a specific error: 402 with code insufficient_credits, returned at submit time. An agent can check first with dry_run=true, which previews admission and cost without submitting the job.

Arcads facts are from its MCP help article (June 26, 2026); Sume facts from Errors and rate limits and MCP tools and gates, read 2026-10-01.

What exactly does Sume return when the balance is short?

Status 402, code insufficient_credits: the balance is not sufficient for the requested generation. The admission docs say the submit fails before provider work starts. Error bodies carry a request id that is safe to share with support.

How can an agent check before it submits?

Will a top-up fix a queue or concurrency error?

No. The admission docs say prepaid top-ups do not raise the processing concurrency limit, which is plan-only. A 429 queue_full is a different error from 402.

What should I do when I get a 402?

The admission docs list the fixes as upgrading the plan, waiting for included Gen$, or submitting a cheaper request. See insufficient credits 402 for the fix path.