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Gemini 3.8 Flash

Runs MCP tools

Google’s newest Flash model, released 2 September 2026 and its third Flash release in six weeks. Google calls it its best reasoning and coding model yet, at the speed of 3.7 Flash.

Vendor
Google
Released
2 September 2026
Context
1M tokens
Input
Text, image, video, audio, file

Paste a server URL, pick a model, and watch it call your tools in a real conversation. No install.

No server of your own? Leave it blank and use one of the public mock servers.

In your browser

MCP Agent Studio

Server has a public URL? Chat with Gemini 3.8 Flash on it, watch every tool call, and compare models side by side.

Open MCP Agent Studio →

On your computer

MCP Playground Desktop

Server runs on localhost or over stdio? The browser can’t reach it. The desktop app can, with Gemini 3.8 Flash in Agent Studio. Download free

Mac (Apple Silicon)Mac (Intel)Windowsor Microsoft Store

MCP Evals

Can Gemini 3.8 Flash actually complete tasks with your server?

One chat shows the tool calls work. An eval writes real tasks from your tool schemas, has Gemini 3.8 Flash drive each one, and reports where it got the wrong answer even though every call succeeded. Pick Gemini 3.8 Flash as the driver.

Run evals →See a sample

What Gemini 3.8 Flash is

Gemini 3.8 Flash succeeds 3.7 Flash. It has a 1M-token window, up to 64K tokens of output, and takes text, image, video, audio and file input. Google released it alongside 3.8 Flash Cyber, a separate variant for vulnerability detection and patching that is limited to vetted defenders and not available here.

What Google says

  • Terminal-bench 2.1: 89.4%.
  • DeepSWE v1.1: 73.7%.
  • Terminal-bench 4.0: 19.1%.
  • GDPval-AA v2: 1545, up from 1482 for 3.7 Flash.
  • A significant gain in prompt-injection robustness on Gray Swan’s benchmark, by Google’s account.

These are the vendor’s own claims, not measurements of ours. Run the model against your own server to find out whether they hold for your tools.

How it reaches MCP

  • The Gemini API, whose Python and JavaScript SDKs can take an MCP session as a tool directly. Google marks this experimental.
  • MCP Playground’s Agent Studio: paste your server URL above and run Gemini 3.8 Flash against it in the browser, with no Google key
  • Gemini CLI, Google’s terminal agent, which acts as an MCP client

What to watch for

  • Google’s own numbers split sharply: 89.4% on Terminal-bench 2.1 and 19.1% on Terminal-bench 4.0. Short tool tasks may go well and long multi-step chains may not. Test the length of chain your server actually needs.
  • MCP tool results are a prompt-injection route, and Google says 3.8 Flash is significantly more robust on Gray Swan’s benchmark. That is worth checking against your own server’s outputs rather than assuming.
  • Three Flash releases in six weeks means the model behind a “latest” alias moves quickly. Pin gemini-3.8-flash if you need results to stay comparable.

Run 3.8 Flash and 3.7 Flash on the same four-step task against the complex-schema mock: create_user_profile, process_order, analyze_data, then configure_workflow. The Terminal-bench split suggests the later steps are where the two will differ. All the mock servers →

Available here

ModelModel ID
Gemini 3.8 Flashgoogle/gemini-3.8-flash

Go deeper

Frequently asked questions

Does Gemini 3.8 Flash support MCP?
Yes. Google’s Gemini SDKs for Python and JavaScript can use an MCP session as a tool directly, marked experimental, and any MCP client can drive it through function calling. You can run it against your own server here without a Google key.
What is Gemini 3.8 Flash Cyber?
A separate variant built for finding and patching software vulnerabilities, released the same day. Access is limited to vetted defenders through Google’s application programme, and it is not available here.
What changed from Gemini 3.7 Flash?
Google reports gains across software engineering, agent tasks and multi-step reasoning at the same speed, including GDPval-AA v2 up from 1482 to 1545. Both are available here, so you can compare them on your tools.
Can Gemini 3.8 Flash read audio and video from MCP tools?
It accepts audio and video input, but MCP tool results come back as text, image or embedded resources. Whether audio or video reaches the model depends on your client passing it through, so test with text and image results first.

Sources