AI Developer Tools
OpenAI Tool Schema Validator
Inspect one OpenAI Responses API function tool definition. The checker verifies its top-level shape and common strict-mode object rules.
✓ Every tool runs in your browser. We do not upload your input or output.
Keyboard shortcuts
Ctrl/⌘ + Enter: process
Ctrl/⌘ + Shift + F: full screen
Esc: exit full screen
Ctrl/⌘ + F in editor: search
How to use
- Paste a single function tool JSON object, not an entire API request.
- Run the checker and fix any missing name, parameters, or object properties.
- If strict is true, include additionalProperties false and list every property in required.
- Review current OpenAI documentation and test against the API before shipping.
Examples
Check a weather function
A strict object with no fields has an empty required list and disallows extra fields.
{"type":"function","name":"get_weather","parameters":{"type":"object","properties":{},"required":[],"additionalProperties":false},"strict":true}Valid OpenAI function tool shape
Review a function definition before sending it
A Responses API function tool describes an action with a name and a JSON Schema for its arguments. This checker accepts the function tool object itself and verifies the fields most likely to cause a structural mistake. When strict mode is enabled, it checks that each object schema disallows extra properties and lists every defined property as required. Nested object properties and array item objects receive the same check.
The checker is deliberately local and limited. It cannot tell whether a model supports a particular schema feature, whether your description is helpful, or whether the live API will accept a request. Use it as an early review step, then compare with the official OpenAI function calling guide and run an integration test. The content of your tool definition stays in the browser. The sample is a shape example, not a live request.
Frequently asked questions
Does this call OpenAI?
No. It only checks JSON locally in your browser.
Does a valid result guarantee API acceptance?
No. Models and API versions can add limits beyond these structural checks.
Why is strict mode rejecting optional fields?
In strict mode, object properties must be required; optional values can be represented with a nullable type.
Can I paste a tools array?
Use one function tool object at a time.