How can I ensure n8n's AI agent passes the sessionId along with chatInput to the workflow_tool?

Below is some guidance to help ensure that your workflow tool receives both the chat input and session ID.

Why It’s Happening

Even though you’ve instructed the AI agent via the system prompt to include both the chat input and session ID, the agent’s output (or the tool call) is actually generated based solely on the content provided (i.e. {{ $json.chatInput }}). In other words, the extra variable ({{ $json.sessionId }}) isn’t automatically appended to the output unless it is present in the data passed to the call.

Recommended Solutions

1. Update the Field Mapping on the Workflow Tool Node
   Instead of relying solely on the agent’s response to forward the session ID, explicitly combine the two variables in your workflow tool node.

   For example, adjust the “fields” configuration in your workflow tool node to something like:

   JSCopied
   {
     "chatInput": "={{ $json.chatInput + ' ' + $('Window Buffer Memory').item.json.sessionId }}"
   }

   This way, the workflow tool receives a string that contains both the user’s chat input and the session ID from your memory node.

2. Modify the System Prompt (if applicable)
   If you want the AI agent itself to output a JSON object that explicitly contains both values (for example, in a JSON blob), you could modify your system prompt to instruct the agent to return the following structure:

   JSONCopied
   {
     "chatInput": "{{input}}",
     "sessionId": "{{sessionId}}"
   }

   However, note that the agent may only use what was given from the Chat Trigger node (which in your case is only the chat input).

   A more reliable approach is to combine the data at the workflow level (as shown in solution 1).

Summary

The AI agent is currently passing only the chat input because that’s the only data it receives from the Chat Trigger. To pass the session ID along with the chat input, you need to update the field mapping in the call_n8n_workflow_tool node (or use an intermediate node) to combine these values. This approach ensures that the expected data (chat input and sessionId) is sent to your workflow tool, enabling proper memory handling.

Give this a try, and it should address the issue you’re facing with not having the session ID passed along.

Below is an explanation and some steps to help ensure your session ID is passed along to the workflow tool as expected.

Why the Session ID May Not Be Passed

Even though you instruct the agent (via its system prompt) to send both {{ $json.chatInput }} and {{ $json.sessionId }}, the tooling behavior depends on how the nodes are connected and how memory is attached. In many cases, if the memory isn’t properly attached or configured between the Chat Trigger and tool nodes, the agent might only send the chat input.

Steps to Fix the Issue

1. Attach the Same Memory Node to Both Ends
   When using the Chat Trigger node with memory (via a Windows Buffer Memory node), ensure that the same memory node is attached to both the Chat Trigger and the agent (or tool) node. This connection is key if you require the session ID (set in the memory node) to be part of the payload when the workflow tool is called.

   • In your Chat Trigger node, set Load Previous Session (if applicable) to “From Memory.”
   • Attach your Windows Memory Buffer node to the Memory connector of the Chat Trigger.
   • Attach the same Windows Memory Buffer node to the Memory connector of the agent node that calls the workflow_tool.
   • In the Windows Memory Buffer node, set Session ID to Take from previous node automatically (or define it explicitly if needed).

2. Verify Your Expression Compatibility
   If you’re retrieving the session ID from an expression (for example, using {{ $json.sessionId }}) you need to ensure that the expression is available and evaluates correctly in both nodes (the origin and the workflow tool). If the expression isn’t compatible with one node, consider using separate memory nodes where you can customize the session ID expression as required.

3. Consider Using the Metadata Field for Embedding
   If your chat is embedded on your website, you can also pass extra information (such as the session ID) via the metadata field when calling createChat. For instance, you can pass the session ID as follows:

   JAVASCRIPTCopied
   createChat({
     webhookUrl: 'YOUR_PRODUCTION_WEBHOOK_URL',
     metadata: {
       sessionId: 'YOUR_SESSION_ID_VALUE'
     }
   });

   This metadata will then be available in the Chat Trigger output and can be leveraged downstream.

Summary

To ensure your workflow tool receives the session ID along with the chat input:

• Attach the same Windows Memory Buffer node to both the Chat Trigger and the relevant agent/tool node.
• Configure the memory node to automatically take the session ID from the previous node.
• Ensure your expressions (e.g., {{ $json.sessionId }}) work consistently across all nodes.
• Optionally, use the metadata field during chat initialization to pass the session ID.

By following these steps, the session ID from the parent node should be properly forwarded to your workflow tool, enabling the memory functionality you need.