Interactive converter

OpenAI to Gemini function declaration converter

Compile OpenAI function tools into Gemini-compatible declarations and expose unsupported schema keywords.

Tool wrapper conversionNullable normalizationUnsupported keyword reportNo schema upload

Reviewed 29 August 2026Source: Gemini function calling guide

The compiler removes strict-only wrapper details, normalizes nullable types, and reports JSON Schema features outside Gemini’s supported subset.

Read the schema and its provider wrapper as one contract. APITC distinguishes target requirements from portable JSON Schema, applies mechanical repairs only when intent is recoverable, and identifies transformations that can change meaning.

Diagnostic procedure

Repair the schema, then recompile.

01
Detect the OpenAI shape
Flat Responses tools and nested Chat tools are both accepted.
02
Normalize the schema
Provider-only constraints are removed or translated where equivalent.
03
Review lossy changes
Every dropped constraint remains visible in diagnostics.

Before

{"type":"function","name":"lookup","strict":true,"parameters":{"type":"object","additionalProperties":false,"properties":{"id":{"type":["string","null"]}},"required":["id"]}}

Target-safe shape

{"type":"function","name":"lookup","parameters":{"type":"object","properties":{"id":{"type":"string","nullable":true}},"required":["id"]}}

Interactive check

Run the schema against a real target.

Paste JSON, choose a target, and inspect the compiled shape and every portability warning before copying the result.

Contract compilerlocal browser runtime

Compile target

01 Source contract APITC canonical

02OpenAI strict

80compatibility

0 errors · 2 fixes · 0 warnings

fix$.inputSchemaClose this object

OpenAI strict requires additionalProperties: false on every object.

fix$.inputSchemaRequired array is incomplete

Strict mode requires every property in required. APITC will make limit nullable.

≈ 97 tokens compiled · input never leaves this tab

No account · no upload · no endpoint calledOpen the full tool schema compiler and operating notes →

FAQ

Before you ship

Does APITC upload my schema?

No. Parsing, diagnostics, and compilation run in your browser tab.

Is the compiled result guaranteed to preserve meaning?

Safe repairs are deterministic. When Gemini cannot express a source constraint, APITC labels the transform as lossy instead of hiding it.

Protocol behavior checked against the Gemini function calling guide. Recheck your pinned provider/API version before production deployment.

Repair the schema, then recompile.

Detect the OpenAI shape

Normalize the schema

Review lossy changes

Run the schema against a real target.

Before you ship