OpenAI schema error
Fix “additionalProperties is required to be supplied and to be false”
Diagnose and repair OpenAI strict tool schemas missing additionalProperties: false, including nested objects.
OpenAI strict mode closes every object. Setting the keyword only on the root is not enough: nested object parameters must also declare additionalProperties: false.
Read the schema and its provider wrapper as one contract. APITC distinguishes target requirements from portable JSON Schema, applies mechanical repairs only when intent is recoverable, and identifies transformations that can change meaning.
Diagnostic procedure
Repair the schema, then recompile.
- 01
Find every object node
Inspect the root, nested properties, array item objects, and union branches—not just the top-level schema.
- 02
Close each object
Add additionalProperties: false beside type and properties on every object node.
- 03
Recheck required
Strict mode also expects every declared property in required; represent optional values with null.
{"type":"object","properties":{"user":{"type":"object","properties":{"id":{"type":"string"}}}}}{"type":"object","properties":{"user":{"type":"object","properties":{"id":{"type":"string"}},"required":["id"],"additionalProperties":false}},"required":["user"],"additionalProperties":false}$.inputSchemaClose this objectOpenAI strict requires additionalProperties: false on every object.
$.inputSchemaRequired array is incompleteStrict mode requires every property in required. APITC will make limit nullable.
No account · no upload · no endpoint calledOpen the full tool schema compiler and operating notes →
FAQ
Before you ship
Does APITC upload my schema?
No. Parsing, diagnostics, and compilation run in your browser tab.
Is the compiled result guaranteed to preserve meaning?
Safe repairs are deterministic. When OpenAI cannot express a source constraint, APITC labels the transform as lossy instead of hiding it.
Protocol behavior checked against the OpenAI function calling guide. Recheck your pinned provider/API version before production deployment.