[Bug]: Unity MCP (Model Context Protocol) tool calls failing with "unsupported call"

[BuKuSiShen]

What happened?

Environment:

• Windows, PowerShell
• Unity project with MCP For Unity integration
• Codex agent with mcp__unityMCP__* tools available in the tool list

Problem:
Every tool call to mcp__unityMCP__* (e.g., mcp__unityMCP__manage_gameobject, mcp__unityMCP__shell_command) returns:

<tool_result>unsupported call: </tool_result>

The tool name attribute in

• I am unable to make ANY tool calls in this session — every call returns unsupported call: with an empty tool name="".
So I can't reach Unity MCP, PowerShell, or anything else right now.

Reproduction steps

1.Open MCP for Unity and start Server.
2.in the PowerShell,input "create a red cube in current scene"
3.console return <tool_result>unsupported call: </tool_result>

The tool name attribute in

• I am unable to make ANY tool calls in this session — every call returns unsupported call: with an empty tool name="".

Unity version

2022.3.62f3

MCP for Unity package version

9.7.3

Python server version

No response

MCP client

Codex

Transport

HTTP (default)

OS

Windows

Relevant logs / console output

Checks

• I searched existing issues and did not find a duplicate
• I included logs / steps to reproduce

[Scriptwonder]

Try restart both server and Codex for a fresh session, and you should find MCP server called Unity MCP in the MCP list in Codex. We have had this problem before, more on the codex side than unity-mcp side I think.