fix: add required field to empty object schemas for OpenAI strict mode#1719
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guoyangzhen wants to merge 2 commits intomodelcontextprotocol:mainfrom
Open
fix: add required field to empty object schemas for OpenAI strict mode#1719guoyangzhen wants to merge 2 commits intomodelcontextprotocol:mainfrom
guoyangzhen wants to merge 2 commits intomodelcontextprotocol:mainfrom
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Problem
When registering a tool with an empty Zod object as inputSchema (e.g. ), the generated JSON schema omits the field. While this is valid JSON Schema, it is incompatible with OpenAI strict JSON schema mode which requires to always be present (even as an empty array ).
This causes tool registration failures when using MCP tools with OpenAI models in strict mode.
Root Cause
Zod omits the field for empty objects. The MCP SDK passes the result through without adjustment.
Fix
In , after calling , check if the result is an object type with defined but no array, and add . This ensures compatibility with OpenAI strict mode while remaining valid JSON Schema.