fastmcp.utilities.openapi.json_schema_converter

Clean OpenAPI 3.0 to JSON Schema converter for the experimental parser.

This module provides a systematic approach to converting OpenAPI 3.0 schemas to JSON Schema, inspired by py-openapi-schema-to-json-schema but optimized for our specific use case.

Functions

convert_openapi_schema_to_json_schema ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/utilities/openapi/json_schema_converter.py#L40" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

convert_openapi_schema_to_json_schema(schema: dict[str, Any], openapi_version: str | None = None, remove_read_only: bool = False, remove_write_only: bool = False, convert_one_of_to_any_of: bool = True) -> dict[str, Any]

Convert an OpenAPI schema to JSON Schema format.

This is a clean, systematic approach that:

1. Removes OpenAPI-specific fields
2. Converts nullable fields to type arrays (for OpenAPI 3.0 only)
3. Converts oneOf to anyOf for overlapping union handling
4. Recursively processes nested schemas
5. Optionally removes readOnly/writeOnly properties

Args:

• schema: OpenAPI schema dictionary
• openapi_version: OpenAPI version for optimization
• remove_read_only: Whether to remove readOnly properties
• remove_write_only: Whether to remove writeOnly properties
• convert_one_of_to_any_of: Whether to convert oneOf to anyOf

Returns:

• JSON Schema-compatible dictionary

convert_schema_definitions ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/utilities/openapi/json_schema_converter.py#L324" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

convert_schema_definitions(schema_definitions: dict[str, Any] | None, openapi_version: str | None = None, **kwargs) -> dict[str, Any]

Convert a dictionary of OpenAPI schema definitions to JSON Schema.

Args:

• schema_definitions: Dictionary of schema definitions
• openapi_version: OpenAPI version for optimization
• **kwargs: Additional arguments passed to convert_openapi_schema_to_json_schema

Returns:

• Dictionary of converted schema definitions