lindy-hello-world

Lindy Hello World

Overview

Build a minimal Lindy AI agent: Webhook Received trigger -> LLM processing -> Slack notification. Demonstrates the three core building blocks every Lindy agent uses: Trigger, Agent Step (prompt + model + skills), and Action.

Prerequisites

• Lindy account at https://app.lindy.ai
• Slack workspace connected (or Gmail for email variant)
• Completed lindy-install-auth setup

Instructions

Step 1: Create Agent via Dashboard

1. Click "New Agent" at https://app.lindy.ai
2. In the prompt field ("How can I help you?"), type:

   When I send a webhook, summarize the message and post it to Slack
   

3. Agent Builder auto-generates the workflow with trigger + action nodes

Step 2: Configure the Webhook Trigger

1. Click the trigger node at the top of the workflow canvas
2. Select Webhook Received
3. Copy the generated URL:

   https://public.lindy.ai/api/v1/webhooks/<unique-id>
   

4. Click Generate Secret — copy immediately (shown once)

Step 3: Add the Slack Action

1. Click "+" to add a step
2. Search for Slack Send Channel Message
3. Authorize your Slack workspace when prompted
4. Configure fields:
   • Channel: #general (or test channel)
   • Message field mode: AI Prompt
   • Instruction:

     Summarize the webhook payload in one sentence.
     Payload: {{webhook_received.request.body}}
     

Step 4: Set the Agent Prompt

Open Settings > Prompt:

You are a webhook summarizer. When you receive a webhook payload,
extract the key information and create a concise one-sentence summary.
Be factual and specific. Do not add opinions or speculation.

Step 5: Test It

curl -X POST "https://public.lindy.ai/api/v1/webhooks/YOUR_ID" \
  -H "Authorization: Bearer YOUR_SECRET" \
  -H "Content-Type: application/json" \
  -d '{
    "event": "order.created",
    "customer": "Jane Doe",
    "amount": 149.99,
    "items": ["Widget Pro", "Adapter Cable"]
  }'

Expected Slack message:

Jane Doe placed a $149.99 order for Widget Pro and Adapter Cable.

Step 6: Verify in Dashboard

Navigate to the Tasks tab in your agent view. Confirm status shows Completed. Click into the task to see each step's input/output for debugging.

Agent Anatomy

Component	Purpose	Hello World Value
Prompt	Core behavioral instructions	"Summarize webhook payloads"
Model	AI engine powering decisions	Default (GPT-4 / Claude / Gemini)
Skills	Available actions & tools	Slack Send Channel Message
Exit Conditions	When the task is "done"	Message sent successfully

Webhook Data Variables

Variable	Contents
{{webhook_received.request.body}}	Full JSON payload
{{webhook_received.request.headers}}	HTTP request headers
{{webhook_received.request.query}}	URL query parameters

Field Configuration Modes

Mode	Behavior	Credit Cost
Auto	Agent determines value from context	Standard
AI Prompt	Natural language instructions generate content	Standard
Set Manually	Exact value, no AI processing	Lower

Variant: Email Instead of Slack

Replace the Slack action with Gmail Send Email:

• To: Set manually or reference a webhook field
• Subject: AI Prompt — "Summary: {{webhook_received.request.body.event}}"
• Body: AI Prompt — "Summarize this event: {{webhook_received.request.body}}"

Error Handling

Issue	Cause	Solution
Webhook returns 401	Missing Authorization header	Add Bearer <secret> header
Slack message not sent	Channel not authorized	Re-authorize Slack in Lindy
Task shows "Failed"	Action misconfigured	Check field references in step config
No task created	Agent not active	Publish/activate the agent
Empty summary	Payload not reaching LLM	Verify {{webhook_received.request.body}} reference

Cost

~1-3 credits per invocation on basic models. Free tier (400 credits/month) supports ~130-400 test runs per month.

Resources

• Getting Started 101
• Webhook Triggers Academy
• Lindy Documentation

Next Steps

Proceed to lindy-core-workflow-a for a full multi-step agent workflow.