# Gemini 3.8 Flash API on TokenRa

Model ID: `gemini-3.8-flash`
Get an API key: https://tokenra.io/register?utm_source=llms-agent&utm_medium=model-llms
Updated: 2026-10-30

> Gemini 3.8 Flash is Google's fast multimodal Gemini model. On TokenRa it answers through OpenAI Chat Completions and Anthropic Messages. It thinks before answering but does not return the reasoning text.

- Provider: Google
- Type: Text model
- API formats: Chat Completions, Messages
- Input: Text, image
- Output: Text

## Pricing

Rates in the TokenRa console when this file was last updated, in US dollars for the default group. The live price list is authoritative: https://tokenra.io/pricing (JSON: https://tokenra.io/api/pricing).

- `gemini-3.8-flash`: $0.94 per 1M input tokens, $4.70 per 1M output tokens, $0.09 per 1M cached input tokens

## Capabilities & endpoints

Chat generation through two API formats. Each was called successfully on tokenra.io on 2026-10-23.

- `POST https://tokenra.io/v1/chat/completions`: OpenAI SDK with `base_url="https://tokenra.io/v1"`. Auth: `Authorization: Bearer`. Recommended.
- `POST https://tokenra.io/v1/messages`: Anthropic SDK or Claude Code with base URL `https://tokenra.io`. Auth: `x-api-key` (or Bearer) plus `anthropic-version`.

**Format not available**

- OpenAI Responses (`/v1/responses`) is not available for this model: requests fail with HTTP 400 `contents is required`.

## Example

Set `TOKENRA_API_KEY` to your API key first. The docs page has the same example in Python, JavaScript and Java.

```bash
curl https://tokenra.io/v1/chat/completions \
  -H "Authorization: Bearer $TOKENRA_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gemini-3.8-flash",
    "messages": [
      {"role": "system", "content": "You are a concise technical assistant."},
      {"role": "user", "content": "Explain in two sentences what an API gateway does."}
    ]
  }'
```

## Request parameters

Fields for `POST /v1/chat/completions`. Everything listed was accepted by the model in testing.

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `model` | string | Yes | The model ID to call, for example `gemini-3.8-flash`. |
| `messages` | array | Yes | Conversation messages in order (system, user, assistant, tool). For multi-turn chat, send the earlier turns back in this array. `content` can be a string or an array of `text` and `image_url` parts. |
| `stream` | boolean | No | Return the answer as server-sent events. Default `false`. |
| `stream_options` | object | No | With `{"include_usage": true}`, the last chunk carries `usage` and an empty `choices` array. |
| `max_tokens` | integer | No | Upper limit for generated tokens. Reasoning tokens count toward it: if it is too low the model can spend it all on reasoning and return no text (`finish_reason: "length"`). |
| `max_completion_tokens` | integer | No | Upper limit for all generated tokens, reasoning included. If it is too low the answer can be empty (`finish_reason: "length"`). |
| `temperature` | number | No | Sampling temperature. |
| `top_p` | number | No | Nucleus sampling threshold. Usually tune either this or temperature. |
| `presence_penalty` | number | No | Penalises tokens that already appeared, nudging the model toward new topics. |
| `frequency_penalty` | number | No | Penalises frequent tokens to reduce repetition. |
| `reasoning_effort` | string | No | Reasoning depth such as `low`, `medium` or `high`. The model accepted it in testing; how much it changes the reasoning varies by model. |
| `user` | string | No | Your own end-user identifier for auditing or abuse handling. It is not part of the conversation. |

**Not supported by this model**

- Neither `json_object` nor `json_schema` is enforced: plain text, or JSON inside a Markdown code block, came back. Ask for JSON in the prompt and strip Markdown code fences before parsing.
- Function calling is not available: requests with `tools` return HTTP 400 from the upstream.

### Other formats

| Format | Required fields | Answer location |
| --- | --- | --- |
| Anthropic Messages | `model`, `max_tokens`, `messages` | `content[]` blocks of type `text` |

## Response format

**Example response**

```json
{
  "id": "chatcmpl-1792766122484",
  "object": "chat.completion",
  "created": 1792766122,
  "model": "gemini-3.8-flash",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "An API gateway is the single entry point that receives client requests and routes them to the right backend service. It also handles shared concerns such as authentication, rate limiting and logging."
      },
      "finish_reason": "STOP"
    }
  ],
  "usage": {
    "prompt_tokens": 26,
    "completion_tokens": 58,
    "total_tokens": 84,
    "prompt_tokens_details": {
      "cached_tokens": 0
    },
    "completion_tokens_details": {
      "reasoning_tokens": 21
    }
  }
}
```

| Field | Type | Description |
| --- | --- | --- |
| `id` | string | Completion ID. Include it when you contact support. |
| `object` | string | `chat.completion`, or `chat.completion.chunk` when streaming. |
| `created` | integer | Unix timestamp in seconds. |
| `model` | string | The model that produced the answer. |
| `choices[].message.content` | string | The answer text. |
| `choices[].finish_reason` | string | `stop`, `length` or `tool_calls`. |
| `usage` | object | `prompt_tokens`, `completion_tokens`, `total_tokens`, plus `prompt_tokens_details.cached_tokens` and `completion_tokens_details.reasoning_tokens`. |

With `stream: true` the answer arrives as `data:` lines of `chat.completion.chunk` objects and ends with `data: [DONE]`.

## Errors & limits

### Common errors

| HTTP | error.code | Meaning | What to do |
| --- | --- | --- | --- |
| `401` | - | Missing, wrong or deleted API key. The message is `Invalid token`. | Check the `Authorization: Bearer` header and the key in the console. |
| `400` | - | The body is not valid JSON. | Fix the JSON and send `Content-Type: application/json`. |
| `500` | `invalid_request` | A required field is missing, for example `messages`. | Add the field named in the message. Retrying will not help. |
| `403` | `insufficient_user_quota` | Your balance or plan quota is used up. | Top up in the console, then retry. |
| `503` | `model_not_found` | Unknown model ID, or no channel serves it for your group. | Check the ID in the model list or with `GET /v1/models`. |
| `429` | - | Too many requests. | Back off exponentially and retry. |
| `5xx` | - | The upstream provider failed or timed out. | Retry a few times; keep the request id if it persists. |

### Limits and notes

- Image input was tested with an `image_url` part that points to a public HTTPS image.
- The model reasons before answering but returns no reasoning text. `usage.completion_tokens_details.reasoning_tokens` shows how many reasoning tokens were used; they count toward `max_tokens` and are billed as output.
- Some requests in testing failed with HTTP 504 (`bad_response_status_code`) and a few took about two minutes. Retry 504 responses and use a client timeout of at least 180 seconds.
- `finish_reason` comes back in upper case (`STOP`) instead of `stop`.

## More

- [Gemini 3.8 Flash API docs page](https://tokenra.io/docs/gemini-3.8-flash.html): parameter tables and code samples in cURL, Python, JavaScript and Java
- [API basics](https://tokenra.io/docs/common.html): base URL, authentication, errors, retries
- [Quickstart](https://tokenra.io/docs/quickstart.html): create a key and send a first request
- [All models](https://tokenra.io/docs/models.html): every model ID
- [Chinese version of this guide](https://tokenra.io/zh/docs/gemini-3.8-flash/llms.txt)
- [Site index for agents](https://tokenra.io/llms.txt)

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Canonical version of this document: https://tokenra.io/docs/gemini-3.8-flash/llms.txt