Interactive converter

MCP tool to OpenAI strict function converter

Convert MCP inputSchema tools to OpenAI strict functions and identify protocol semantics that do not carry over.

inputSchema → parametersRecursive strict repairAnnotation gapOutput contract warning

Reviewed 29 August 2026Source: OpenAI function calling guide

Input arguments translate cleanly only after strict repairs. MCP outputSchema and annotations have no direct OpenAI function-schema equivalent, so APITC reports them as contract-level portability gaps.

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
Import the MCP tool
Paste a tools/list entry or a single tool definition.
02
Repair strict input
All objects are closed and optional fields become nullable-required.
03
Review lost protocol data
Keep output and side-effect semantics in your application layer.

Before

{"name":"lookup","description":"Find a record","inputSchema":{"type":"object","properties":{"id":{"type":"string"}}}}

Target-safe shape

{"type":"function","name":"lookup","description":"Find a record","parameters":{"type":"object","properties":{"id":{"type":["string","null"]}},"required":["id"],"additionalProperties":false},"strict":true}

Interactive check

Run the schema against a real target.

Paste JSON, choose a target, and inspect the compiled shape and every portability warning before copying the result.

Contract compilerlocal browser runtime

Compile target

01 Source contract APITC canonical

02OpenAI strict

80compatibility

0 errors · 2 fixes · 0 warnings

fix$.inputSchemaClose this object

OpenAI strict requires additionalProperties: false on every object.

fix$.inputSchemaRequired array is incomplete

Strict mode requires every property in required. APITC will make limit nullable.

≈ 97 tokens compiled · input never leaves this tab

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.

Repair the schema, then recompile.

Import the MCP tool

Repair strict input

Review lost protocol data

Run the schema against a real target.

Before you ship