Why isn’t n8n’s Tools Agent passing data to mysql_create_table (undefined error)?

Below are some troubleshooting steps you can try to resolve the issue where the Tools Agent isn’t passing any data to your mysql_create_table tool:

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1. Check the Prompt Configuration

If you’re using a prompt mode that automatically takes input from a previous node, ensure that the expression or data source you reference actually returns a valid (non-null) value. For example, if you’re using Take from previous node automatically, make sure that the field generating the SQL or table name isn’t empty. Alternatively, try switching to Define below and explicitly reference the data you need.

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2. Verify Node Connectivity

Confirm that the Tools Agent has a connected Chat Model sub-node. An unconnected or misconfigured Chat Model could result in missing data being passed along. In the Tools Agent’s interface, click the + Chat Model (or the attached connector) and select an appropriate Chat Model.

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3. Re-Add or Update the MySQL Node

Sometimes the issue can be resolved by ensuring you’re using the latest version of the MySQL node. Remove your MySQL node from the workflow and then re-add it. This ensures that any recent improvements or bug fixes (such as proper handling of tool input data) are applied.

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4. Validate the Data Flow

Check the logs and the input data being passed between the Tools Agent and the MySQL node. If the tool’s input appears empty (or undefined), trace back:

• Inspect the output of the node that generates the SQL command to confirm it’s not returning a null or empty value.
• If you are using expressions, ensure they reference valid field names and values.

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5. Test with Manual Query

As a diagnostic step, try manually passing a SQL query to the MySQL node (using a Define below prompt setting) to confirm that the node works correctly in isolation. For example, set the prompt manually to something like:

SQLCopied
CREATE TABLE cars (
  id INT AUTO_INCREMENT PRIMARY KEY,
  model VARCHAR(255),
  year INT
);

This can help verify that the issue indeed lies in the data not being passed from the Tools Agent.

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By following these troubleshooting steps, you should be able to determine whether the problem is with the prompt/expression configuration in your Tools Agent or with the MySQL node setup. Adjusting the configuration and ensuring data isn’t missing (or null) at each step will help resolve the “undefined” error you’re seeing.