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Gemini 3 5 Flash Api Developer Guide 2026

Evidence notes document the bounded local or source-based checks behind an Effloow article. They are not product endorsements, legal advice, or benchmark claims.

Date: 2026-05-27 Track: tool-scout Slug: gemini-3-5-flash-api-developer-guide-2026

What was verified

Source-based scouting. No live API calls (no GEMINI_API_KEY in this environment).

Key facts verified from official sources

Fact Source Verified
Model ID gemini-3.5-flash ai.google.dev/gemini-api/docs/models/gemini-3.5-flash
GA at Google I/O May 19 2026 marktechpost.com, magicshot.ai
$1.50 input / $9.00 output per 1M tokens pricepertoken.com, tokenmix.ai
$0.15 cached input / $9.00 output pricepertoken.com
1,048,576 input context window ai.google.dev official docs
65,536 output token limit ai.google.dev official docs
76.2% Terminal-Bench 2.1 marktechpost.com, llm-stats.com
83.6% MCP Atlas benchmark buildfastwithai.com
84.2% CharXiv Reasoning marktechpost.com
4x faster output than comparable frontiers chatforest.com
Supports text + image + audio + video input, text output official docs
Available on: Gemini API, AI Studio, Vertex AI, Antigravity, GEAP official docs
Outperforms Gemini 3.1 Pro on coding and agentic benchmarks marktechpost.com
Requires google-genai SDK v2.0.0+ official docs

API code patterns confirmed

  • Interactions API (recommended for stateful agentic use): client.interactions.create({ model: "gemini-3.5-flash", ... })
  • GenerateContent API: client.models.generate_content(model="gemini-3.5-flash", ...)
  • thinking_level parameter (replaces thinking_budget from prior versions) confirmed from official docs

Breaking changes for existing Gemini 3.1 Pro users

  • SDK: google-genai v2.0.0+ required (breaking changes to Interactions API)
  • Parameter: thinking_budgetthinking_level
  • Function call responses: id, name, and response must all match in responses

What was NOT verified

  • Live API calls (no key available)
  • Actual tokens/second measurement
  • Antigravity 2.0's 12x internal optimization (unverified secondary claim)

Sources

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This note supports the public article and records what was actually checked.

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