Task: AI: Conversational agent with custom tool written in JavaScript 

n8n workflow JSON:
{"meta":{"instanceId":"408f9fb9940c3cb18ffdef0e0150fe342d6e655c3a9fac21f0f644e8bedabcd9","templateCredsSetupCompleted":true},"nodes":[{"id":"912b279c-30e5-4991-92ab-040fc1e89c7a","name":"When clicking ‘Test workflow’","type":"n8n-nodes-base.manualTrigger","position":[-60,0],"parameters":{},"typeVersion":1},{"id":"749d8762-d213-4dd3-b404-4c6518fcd28f","name":"When chat message received","type":"@n8n/n8n-nodes-langchain.chatTrigger","position":[-60,200],"webhookId":"c2e664e6-645f-422a-99d3-cf0f4c53c345","parameters":{"options":{}},"typeVersion":1.1},{"id":"1eeff044-b914-40f7-8d37-8b69007862cd","name":"AI Agent","type":"@n8n/n8n-nodes-langchain.agent","position":[460,0],"parameters":{"text":"={{ $json.chatInput }}","options":{},"promptType":"define"},"typeVersion":1.8},{"id":"ac34f7f0-d1dc-4ffb-8f49-6ddc925e97bc","name":"Debug Input","type":"n8n-nodes-base.set","position":[160,0],"parameters":{"options":{},"assignments":{"assignments":[{"id":"25d97d59-b0cf-46ae-916d-18059b3d6847","name":"chatInput","type":"string","value":"Return a random color but not green or blue"}]}},"typeVersion":3.4},{"id":"a410a0a5-1ea1-4ade-a32c-8f6fd959bae8","name":"OpenAI Chat Model","type":"@n8n/n8n-nodes-langchain.lmChatOpenAi","position":[440,200],"parameters":{"model":{"__rl":true,"mode":"list","value":"gpt-4o-mini"},"options":{}},"credentials":{"openAiApi":{"id":"8gccIjcuf3gvaoEr","name":"OpenAi account"}},"typeVersion":1.2},{"id":"923b1597-2e9c-4c38-b3bb-7d6dffb52e4a","name":"Code Tool","type":"@n8n/n8n-nodes-langchain.toolCode","position":[660,200],"parameters":{"name":"my_color_selector","jsCode":"const colors = [\n    'red',\n    'green',\n    'blue',\n    'yellow',\n    'pink',\n    'white',\n    'black',\n    'orange',\n    'brown',\n];\n\nconst ignoreColors = query.split(',').map((text) => text.trim());\n\n// remove all the colors that should be ignored\nconst availableColors = colors.filter((color) => {\n    return !ignoreColors.includes(color);\n});\n\n// Select a random color\nreturn availableColors[Math.floor(Math.random() * availableColors.length)];\n","description":"Call this tool to get a random color. The input should be a string with comma-separated names of colors to exclude."},"typeVersion":1.1}],"pinData":{},"connections":{"Code Tool":{"ai_tool":[[{"node":"AI Agent","type":"ai_tool","index":0}]]},"Debug Input":{"main":[[{"node":"AI Agent","type":"main","index":0}]]},"OpenAI Chat Model":{"ai_languageModel":[[{"node":"AI Agent","type":"ai_languageModel","index":0}]]},"When chat message received":{"main":[[{"node":"AI Agent","type":"main","index":0}]]},"When clicking ‘Test workflow’":{"main":[[{"node":"Debug Input","type":"main","index":0}]]}}}