🤖 feat: enable native Google tools for Gemini 3

[ThomasK33]

Summary

Enable provider-native Google Search and URL Context for direct Google Gemini 3 models, so Gemini 3 agents can use Google's built-in web/context tools alongside Mux function tools.

Background

Google's current Gemini 3 tooling supports combining provider-native tools with function calling. The previous Mux implementation had a stale comment that prevented Google native tools from being instantiated, so Gemini models only received Mux's runtime web_fetch and no native Google Search.

Implementation

• Add a shared supportsGoogleNativeToolsWithFunctionTools() gate for Google native tools.
• Gate native Google tools to Gemini 3 model IDs, including the valid models/gemini-3.5-flash spelling.
• Instantiate google.tools.googleSearch({}) and google.tools.urlContext({}) for supported direct Google models.
• Keep Gemini 2.5 and future Gemini 4 IDs off the native-tool path until the installed Google SDK serializes mixed native/function tools for them.
• Add tokenizer fallback handling/tests for schema-less provider-native tools.

Validation

• bun test src/common/utils/tools/toolDefinitions.test.ts src/common/utils/tools/tools.test.ts
• bun x jest src/node/utils/main/tokenizer.test.ts --runInBand
• make typecheck
• make static-check
• Ran deep-review-workflow and fixed the three verified findings: Gemini 4 over-gating, models/... Gemini 3 IDs, and unreachable url_context token fallback.

Risks

Medium-low. This changes tool availability for Google Gemini 3 direct-provider sessions only. The main risk is provider SDK compatibility, so the gate intentionally tracks the currently verified Gemini 3 mixed native/function path rather than pre-enabling future major versions.

---

Generated with mux • Model: openai:gpt-5.5 • Thinking: xhigh • Cost: $20.40

[ThomasK33]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Hooray!

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".