JSON Schema → Tool Use Converter (Claude / OpenAI / Gemini)
Convert JSON Schema (or build from a form) to Anthropic Claude tool_use, OpenAI function calling, and Google Gemini function declaration formats simultaneously. Form UI to build from scratch or paste existing schema.
100% Free
No signup
Browser-only
5 languages
Dark mode
Usage: drop this JSON into the tools[] array of your SDK call
❓ FAQ
Differences between formats?
Anthropic uses input_schema, OpenAI uses parameters (in function), Gemini wraps in functionDeclarations. Inner JSON Schema is largely the same
strict mode?
Only OpenAI has strict: true. Anthropic / Gemini are best-effort
Multiple tools?
One at a time. Concatenate multiple outputs into your tools[] array
🐛 Found a bug or issue with this tool?
Free to use, no signup. Even just the steps to reproduce are helpful. Reports go directly to the operator and help us fix issues.
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