API Tool Schema Validator
Validate OpenAI and Anthropic function/tool schemas before sending to the API. Catches common mistakes. All in your browser.
Try it with this example
Paste OpenAI or Anthropic tool/function schema JSON. Validate names, types, and structure.
What is this tool?
OpenAI and Anthropic APIs accept tool (function) definitions as JSON schemas. Missing names, invalid parameter types, or malformed structure cause API errors. The API Schema Validator checks your tool definitions before you send them. Paste your schema—OpenAI tools format or Anthropic tools format—and get validation results. Catches missing required fields, invalid types, and common mistakes. Use it when building ChatGPT plugins, Claude tools, or any AI API integration. All validation runs in your browser.
Tool schemas describe functions the AI can call: name, description, and parameters (JSON Schema). The validator ensures the name is present and valid, parameters use allowed types (string, number, boolean, object, array), and the overall structure matches what the API expects. Different providers have slight variations; the tool supports the main formats. Fix reported issues and re-validate until clean. No need to hit the API to discover schema errors.
Use it before deploying an AI integration. When adding new tools to an existing set. When debugging "invalid request" errors—often a schema problem. When onboarding teammates who are new to tool schemas. The validator doesn't execute tools or call the API; it only checks the schema. For full testing, combine with the API Mock Generator or manual API calls.
All validation is client-side. No server, no API key, no data sent. Paste your schema, get feedback. Keep schemas in version control and validate as part of CI if possible. For the latest requirements, check provider docs—APIs evolve. This tool catches the common mistakes. Bookmark it for AI tool development.
Essential for ChatGPT plugins and Claude tools.