SchemaFit

What is SchemaFit?

SchemaFit is an MIT-licensed CI linter for LLM structured-output schemas. It checks JSON Schema, tool definitions, and response_format schemas against provider-specific constraints before runtime. It catches unsupported keywords, nesting issues, required/optional mismatches, and portability problems across OpenAI, Anthropic, Gemini, Mistral, and Cohere, so teams can fail PRs instead of production calls.