OpenAI models - error: Received tool input did not match expected schema

[lumeora]

Hey!

Since yesterday I have problems with the OpenAI models in my AI Tools Agent node. On Sunday it worked and I didn’t change anything.

Almost every workflow ends with a “Received tool input did not match expected schema”.

In the logs I can see that the AI wrote a response, but after that the output is this error:

If I switch to Claude 3.7 Sonnet everything works again, actually it works better than GPT-4o or GPT-4o-mini, but of course it costs much more, so I would switch back to an OpenAI model. I also tried with the new GPT-4.1 today, but the result is the same error.

Do other users have the same problem? What could be the reason for that if I didn’t change anything?

Information on your n8n setup

• n8n version: 1.86.1
• Database (default: SQLite):
• Running n8n via: elest.io

[Tylon]

non of three Ai models used the mcp client execute tool, even it is the only tool too use. Why?

[cyril1]

Hello, I have the same problem and I need a solution too

[lumeora]

I duplicated the whole workflow and after that it worked again. I don’t know if this is the solution for everyone, but for me this helped.

[Alfredo_Rapetta]

I have been having the same problem since yesterday, for absolutely no reason, and with no change. I duplicated the workflow just as you said, why not, and now it’s working again. I think this should be looked at to have a more reliable system.