My variables should be defined but arent, im fairly new to n8n so any help would be apreciated!
Hey @Gesco06 hope all is well, welcome to the community.
Seeing the input would be helpful to understand why your expressions are expressing 
Also try to embed the workflow, so we can take a look.
{
"name": "insta scrape",
"nodes": [
{
"parameters": {
"options": {}
},
"type": "@n8n/n8n-nodes-langchain.chatTrigger",
"typeVersion": 1.1,
"position": [
80,
0
],
"id": "63a65207-3d06-4761-9d23-a90f2c70f483",
"name": "When chat message received",
"webhookId": "3fd0b86f-bb0f-47c7-8193-586addff7694"
},
{
"parameters": {
"options": {}
},
"type": "@n8n/n8n-nodes-langchain.agent",
"typeVersion": 2,
"position": [
460,
0
],
"id": "c01da2fc-2238-40fd-a3c5-ceefddcb7f0d",
"name": "AI Agent"
},
{
"parameters": {
"model": {
"__rl": true,
"value": "gpt-4o-mini",
"mode": "list",
"cachedResultName": "gpt-4o-mini"
},
"options": {}
},
"type": "@n8n/n8n-nodes-langchain.lmChatOpenAi",
"typeVersion": 1.2,
"position": [
300,
220
],
"id": "82dbcfb3-aece-4a22-a082-dacacb03786d",
"name": "OpenAI Chat Model",
"credentials": {
"openAiApi": {
"id": "nFeL6mVnmZyJVojK",
"name": "OpenAi account 2"
}
}
},
{
"parameters": {},
"type": "@n8n/n8n-nodes-langchain.memoryBufferWindow",
"typeVersion": 1.3,
"position": [
420,
220
],
"id": "5cbd481e-5d6e-4a32-a260-3d7d633f816c",
"name": "Simple Memory"
},
{
"parameters": {
"descriptionType": "manual",
"toolDescription": "Use this tool when you want to send an email. Assign the email address from the message to: {{ $fromAI('placeholder_email')}}. Extract the subject line and assigned it to: {{ $fromAI('placeholder_subject')}}. The message that we went to send in the email needs to be assigned to:{{$fromAI('placeholder_msg')}}.",
"sendTo": "={{$fromAI('placeholder_email')}}",
"subject": "={{ $fromAI ('placeholder_subject')}}",
"message": "={{$fromAI('placeholder_msg')}}",
"options": {}
},
"type": "n8n-nodes-base.gmailTool",
"typeVersion": 2.1,
"position": [
540,
220
],
"id": "add315cd-dbaf-40d8-bd97-54a996b71320",
"name": "Send a message in Gmail",
"webhookId": "3051b5e3-871c-401c-8a9c-a3c765b96542",
"credentials": {
"gmailOAuth2": {
"id": "n3R5JX1xaKUByIXx",
"name": "Gmail account"
}
},
"disabled": true
},
{
"parameters": {
"options": {}
},
"type": "@n8n/n8n-nodes-langchain.toolSerpApi",
"typeVersion": 1,
"position": [
660,
220
],
"id": "482bb42d-7900-46c8-8832-a0fae5b187bd",
"name": "SerpAPI",
"credentials": {
"serpApi": {
"id": "agn1CVRuUwnBT91w",
"name": "SerpAPI account"
}
}
},
{
"parameters": {
"toolDescription": "=When asked for an Instagram search. \nWhen asked for a specific category. Assign {{$json.category}} to what they are asking for. When they ask for email assign {{$json.emails}} to the email they gave. Assign {{$json.results}} to the number if results is what they are asking for.",
"url": "https://serpapi.com/search",
"sendQuery": true,
"queryParameters": {
"parameters": [
{
"name": "api_key"
},
{
"name": "engine",
"value": "google"
},
{
"name": "q",
"value": "=site:instagram.com \"{{$json.category}}\" \"{{$json.emails}}\""
},
{
"name": "google_domain",
"value": "google.com"
},
{
"name": "gl",
"value": "us"
},
{
"name": "hl",
"value": "en"
},
{
"name": "start",
"value": "1"
},
{
"name": "num",
"value": "={{$json.results}}"
}
]
},
"options": {}
},
"type": "n8n-nodes-base.httpRequestTool",
"typeVersion": 4.2,
"position": [
780,
220
],
"id": "2cc8ac62-a37a-454f-a957-1f6fa48a0803",
"name": "HTTP Request"
}
],
"pinData": {},
"connections": {
"When chat message received": {
"main": [
[
{
"node": "AI Agent",
"type": "main",
"index": 0
}
]
]
},
"OpenAI Chat Model": {
"ai_languageModel": [
[
{
"node": "AI Agent",
"type": "ai_languageModel",
"index": 0
}
]
]
},
"Simple Memory": {
"ai_memory": [
[
{
"node": "AI Agent",
"type": "ai_memory",
"index": 0
}
]
]
},
"Send a message in Gmail": {
"ai_tool": [
[
{
"node": "AI Agent",
"type": "ai_tool",
"index": 0
}
]
]
},
"SerpAPI": {
"ai_tool": [
[
{
"node": "AI Agent",
"type": "ai_tool",
"index": 0
}
]
]
},
"HTTP Request": {
"ai_tool": [
[
{
"node": "AI Agent",
"type": "ai_tool",
"index": 0
}
]
]
}
},
"active": false,
"settings": {
"executionOrder": "v1"
},
"versionId": "1786aa06-0108-4792-a5f5-2e73fb99bc4a",
"meta": {
"templateCredsSetupCompleted": true,
"instanceId": "6bdacdbcf936fa15d7823da866e8751945d082f21833fda91a5a0ba7bca2c5d8"
},
"id": "Y39qz6pIy8mzPqU2",
"tags": []
}```This is the whole workflow, thanks for the help!
Where exactly are they defined?
{{ $json }} object in the tool will have access to fields:
- sessionId
- action
- chatInput
If you need the tool to deduce these from the message, try using fromAI() instead.