Retell AI Setup

Retell AI Setup

Retell AI supports two methods to connect with FlowCaptain: MCP Nodes (recommended) and Custom Functions.

Method 1: MCP Node (Recommended)

MCP Nodes let Retell automatically discover all FlowCaptain tools. No manual endpoint configuration needed.

1. Open your Retell agent
2. Add an MCP Node to your agent flow
3. Set the URL to:

   https://api.flowcaptain.ai/mcp
   

4. Set the Authentication header to:

   Authorization: Bearer sk_live_your_api_key
   

5. Save — Retell will auto-discover these tools:
   • check_availability — Check available time slots
   • book_appointment — Book an appointment
   • cancel_appointment — Cancel an existing appointment
   • reschedule_appointment — Reschedule an appointment

Method 2: Custom Function

If you prefer manual control, set up a Custom Function for each action.

Example: Check Availability

1. Add a Custom Function node in your Retell agent
2. Set:
   • Name: checkAvailability
   • URL: https://api.flowcaptain.ai/api/v1/check-availability
   • Method: POST
   • Headers: Authorization: Bearer sk_live_your_api_key
3. Define the parameter:
   • Name: checkAvail (type: string)
   • Description: "The caller's request about appointment availability"
4. Repeat for booking, cancellation, and rescheduling endpoints

Request Format

Retell sends Custom Function requests as:

{
  "args": {
    "checkAvail": "Do you have anything on Monday?"
  }
}

FlowCaptain automatically maps args.checkAvail to the query parameter.

Tips

• MCP Nodes are simpler — one node replaces four Custom Functions
• Use the callerIdNumber parameter to pass the caller's phone number for appointment lookup
• Test your setup by asking the voice bot: "What's available next week?"