Converts one LLM tool/function definition (OpenAI, Anthropic, Gemini, MCP or plain JSON Schema; format auto-detected) into one or more target provider formats. Applies each provider's schema rules: OpenAI strict mode (all fields required, optional fields made nullable, additionalProperties false), Gemini's OpenAPI subset (no $ref, nullable, string enums), $ref inlining and name sanitising. Returns