Errors

Status codes, what causes them, and what to do.

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What your agent reads

Errors return a JSON body with a machine-readable `code` and a human-readable message.

| Status | Code | Cause | What to do |
| --- | --- | --- | --- |
| `400` | `VALIDATION_ERROR` | A parameter is missing or invalid | Fix the request body. Not charged. |
| `401` | `UNAUTHORIZED` | Missing or invalid API key | Check the `Authorization: Bearer` header. Not charged. |
| `402` | `INSUFFICIENT_CREDITS` | Balance too low for this call | Top up or upgrade in Billing. |
| `429` | `RATE_LIMIT_EXCEEDED` | Too many requests | Wait `Retry-After` seconds, then back off. |
| `502` | `SEARCH_UNAVAILABLE` | An upstream failed | Credits are refunded. Retry with backoff. |

Each endpoint page lists the errors specific to it.

Every page: append .md to the URL. Whole site: /llms.txt · /llms-full.txt

Errors return a JSON body with a machine-readable code and a human-readable message.

Status	Code	Cause	What to do
`400`	`VALIDATION_ERROR`	A parameter is missing or invalid	Fix the request body. Not charged.
`401`	`UNAUTHORIZED`	Missing or invalid API key	Check the `Authorization: Bearer` header. Not charged.
`402`	`INSUFFICIENT_CREDITS`	Balance too low for this call	Top up or upgrade in Billing.
`429`	`RATE_LIMIT_EXCEEDED`	Too many requests	Wait `Retry-After` seconds, then back off.
`502`	`SEARCH_UNAVAILABLE`	An upstream failed	Credits are refunded. Retry with backoff.

Each endpoint page lists the errors specific to it.

Let your agent build it

Paste one prompt into Claude Code, Cursor, Codex or Windsurf. It installs Keiro MCP, reads these docs and writes the integration against the real API.

Rate limits

Per-minute limits by tier, the headers we send, and how to back off.

Google SERP

Google search results as clean JSON, with country and language targeting.