AI Agent with Airtable create record tool not working with multi select columns

[Vincent_Teyssier]

Using latest n8n on local setup via npm (pm2)

I have an AI Agent (with a custom system prompt) connected to a Airtable create record tool.
The underlying airtable table has string and multi select columns.

In the airtable tool the settings is to map each column manually.
I have added all fields of the table and let the AI fill them.
Tool description is set automatically as well.

For the string columns it seems to go through, however for the multi select columns, it returns an error.

Sample input of the tool:
{
“text1”: “xxxxxx”,
“multiselect1”: “yyyyy”,
}

Error:

{ “message”: “Invalid input for ‘multiselect1’ [item 0]”, “timestamp”: 1744700318723, “name”: “ExpressionError”, “description”: “‘multiselect1’ expects a array but we got ‘yyyyy’”, “context”: { “nodeCause”: “create-airtable-record” } }

For multi selects it should return an array instead of a string.

I’ve tried to say this explicitly in the system prompt by adding:
For the “multiselect1” field, make sure to return an array containing teh values you want to input. For example: “multiselect1”: [“xxxxx”]

Now it fails at the AI Agent node with Problem in node ‘AI Agent1‘ [ERROR: Received tool input did not match expected schema]

How can I make this work?

[Vincent_Teyssier]

bumping this… has anyone managed to push to a multi select field ?

[TD_2025]

Hi Vincent, did you try to activate Typecast right at the bottom of the Ai Agents node via the options ? Did the trick for a single select at least

[Vincent_Teyssier]

I did try but that was not enough.
I solved it by encasing the expression with square brackets like this:

{{ [$fromAI('location', ``, 'string')] }}