LLM Tool / Function Definition Builder
Describe a function once and get both the OpenAI function-calling schema and the Anthropic tool-use schema, updated live as you type. Everything runs in your browser — nothing is uploaded.
About this tool
Generates tool definitions in the two formats used for function calling today: OpenAI's {"type":"function","function":{…"parameters":{…}}} wrapper and Anthropic's {"name","description","input_schema"} shape. Parameters become JSON Schema properties with type, description, optional enum values, and a required array — the part that's easy to get subtly wrong by hand. Provider formats do evolve, so double-check against the current API docs if a request is rejected.
Your function names, descriptions, and schemas never leave the page — there is no server, no upload, and no tracking of tool inputs. Everything is built in your browser as you type.