Text model · Google

Gemini 3.8 Flash API

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.

Model ID: gemini-3.8-flash
API formats: Chat Completions, Messages
Input: Text, image
Output: Text

Capabilities

Capabilities & endpoints

Chat generation through two API formats. Each was called successfully on tokenra.io on 2026-10-23; pick one to switch the code examples.

POSThttps://tokenra.io/v1/chat/completionsTested

OpenAI SDK with base_url="https://tokenra.io/v1". Auth: Authorization: Bearer. Recommended.

POSThttps://tokenra.io/v1/messagesTested

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.

Request

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

Response format

{
  "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

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.

Capabilities & endpoints

Request parameters

Other formats

Response format

Errors & limits

Common errors

Limits and notes

Related links