LLM Function Schema Generator ⚡ 🔌
Define function name, description, and parameters—get OpenAI and Anthropic tool JSON. Copy or download for your API integration. No sign-up required.
Validation
- Function name is required.
- Function description is required.
- Each parameter needs a name.
Fix validation errors in the form to enable Copy and Download.
Active format: openai; preview length 39
About this function schema builder
LLM function calling lets models invoke tools you define. This builder assembles the JSON Schema properties, required array, and provider-specific wrapper for OpenAI (tools with type function) or Anthropic (tools with input_schema). Add parameters with types, descriptions, and optional string enums; mark fields as required when the model must supply them.
Validation catches missing names, duplicate parameters, and invalid identifiers before you copy. Switch tabs to compare provider formats—all generated locally in your browser.
Frequently asked questions
Does this tool call an AI or send my schema to a server?
No. JSON is built entirely in your browser from the fields you enter. Nothing is uploaded for generation.
What is the difference between OpenAI and Anthropic output?
OpenAI uses a tools array with type function and a parameters object. Anthropic uses name, description, and input_schema. Both follow JSON Schema for properties; this tool generates both from the same form.
Can I add enum values for parameters?
Yes, for string parameters. Enter comma-separated allowed values; they appear in the generated JSON Schema enum array.
Why is Copy disabled?
Fix validation errors first—function name and description are required, and parameter names must be unique valid identifiers.