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The Add Custom Tool feature lets you integrate external applications or APIs with your SigmaMind AI agent by creating custom tool actions. This is especially useful when the application you want to use (such as Zendesk or any other service) is not already available in the SigmaMind AI Marketplace. By adding a custom tool, you enable your agent to communicate directly with external systems, send and retrieve data, and perform real-world operations automatically during conversations. You can:
  • Add a new custom app
  • Create custom tool actions
  • Define dynamic input variables
  • Test API actions
  • Embed and use tools inside your AI agent
This enables your Voice AI agent to perform real-world actions such as booking, rescheduling, fetching data, updating records, and more.

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Step 1: Add a Custom Tool/App

If your app is not available in the marketplace, you can create a custom tool.
Customtool

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Steps:

  1. Open Agent Builder
  2. Click the Manage Tools/Apps
  3. Click Add Custom Tool/App
  4. Enter the following:
FieldDescription
Tool/ App nameName of the external app (e.g., Calendly, Custom CRM)
Description (Optional)Description of the tool
  1. Click Submit Tool/App
The newly created custom tool will appear in your Manage Tools/Apps list.
Apptool

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Step 2: Configure Authentication

Before creating actions, configure authentication based on the app’s API.
Configure Authentication
  1. Click the app or custom tool that you want to configure authentication for.
  2. Click Configure Authentication
  3. Select the required Auth Type
  4. Enter credentials
  5. Click Submit Authentication
    Auth Type
SigmaMind AI will automatically use this authentication in API requests.
For detailed instructions on authentication types and configuration steps, refer to the Overview page

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Step 3: Add Tool Action

Tool actions define what operation the AI agent can perform using the API.
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Steps:

  1. Click Add Tool Actions
  2. Enter the following details:
FieldDescription
Action NameName of the action (e.g., Reschedule Booking)
Description(Optional)What the action does
Endpoint URLAPI endpoint URL
Request MethodGET, POST, PUT, DELETE
HeadersRequired headers from API documentation
BodyRequest payload
Toolaction

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Action Name

Definition:
A unique identifier for the tool action. The agent uses this name internally to trigger the correct API call. Requirements:
  • Must be unique
  • Use snake_case format
  • No spaces allowed
Example: 
get_ticket_details

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Description (Optional)

Definition:
Explains when and why the agent should use this action. This helps the AI understand the correct context for calling the API. Example: 
Use this action to fetch Zendesk ticket details when the user provides a ticket ID.

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HTTP / Request Method

Definition:
Specifies the type of operation to perform on the API. Supported methods:
  • GET → Retrieve data
  • POST → Create data
  • PUT → Update data
  • PATCH → Partially update data
  • DELETE → Remove data
Example: 
GET

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Endpoint URL

Definition:
The API endpoint where the request will be sent. You can use input variables to dynamically insert values. Static example: 
https://api.zendesk.com/api/v2/tickets.json
Dynamic example using input variable: 
https://api.zendesk.com/api/v2/tickets/{{ticket_id}}.json
Here, {{ticket_id}} will be dynamically provided by the agent.

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Headers

Definition:
Headers provide additional information required by the API, such as authentication and content type. Common headers example:
KeyValue
Content-Typeapplication/json
AuthorizationBearer access_token
Example configuration: 
Content-Type: application/json
Authorization: Bearer {{access_token}}

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Query Parameters

Definition:
Query parameters allow you to filter or modify the API response. These are appended to the endpoint URL. Example configuration:
KeyValue
statusticket_status
Final request example: 
https://api.zendesk.com/api/v2/tickets.json?status=open

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Request Body

Definition:
The request body contains the data sent to the API when creating or updating resources. You can use input variables to dynamically pass values.
Requestbody
Example: 
{
  "ticket": {
    "subject": "{{subject}}",
    "description": "{{description}}",
    "priority": "{{priority}}"
  }
}
Runtime example values:
VariableValue
subjectLogin issue
descriptionUser cannot login
priorityhigh

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Input Variables (variable_name)

Input variables are dynamic placeholders written inside double curly braces, variable_name. These placeholders are automatically replaced with real values extracted from the user’s conversation when the API request is executed. The agent automatically fills these values based on:
  • User input
  • Conversation context
  • Agent configuration
Examples: 
{{ticket_id}}
{{email}}
{{subject}}
{{priority}}
Input variables can be used in:
  • Endpoint URL
  • Query Parameters
  • Request Body

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Complete Example: Get Ticket Details

Action Name 
get_ticket_details
Method 
GET
Endpoint URL 
https://api.zendesk.com/api/v2/tickets/{{ticket_id}}.json
Headers 
Content-Type: application/json
Authorization: Bearer {{access_token}}

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How Input Variables Work

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Conversation Example:

User: I want to reschedule my appointment for tomorrow at 10 AM.

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What SigmaMind AI does:

  1. Extracts values from conversation
  2. Maps values to variables
  3. Replaces variables in the API body
  4. Calls the API automatically

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Final API Request Sent:

{
  "start": "2026-03-10T10:00:00Z",
  "end": "2026-03-10T10:30:00Z",
  "eventTypeId": "12345",
  "reason": "User requested reschedule"
}
  1. Click Submit Action
The action is now available for your agent.
You can add new actions to an existing integration in the App Marketplace in the same way, allowing your AI agent to perform additional operations using the connected app.

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Step 4: Test Tool Action

You can test a tool action to verify that the API works correctly before using it in your agent.
Test

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Steps:

  1. Go to Manage Tools/Apps from the Agent Builder
  2. Select the tool (for example, Cal.com)
  3. In the Tool Actions section, locate the action you want to test
  4. Click the Test button next to the action
This opens the Mock Test API screen.
  1. Enter test values for the detected input variables (such as {{start_date}}, {{end_date}}, {{event_type_id}})
  2. Click Test API Action
  3. Review the response to confirm the API is working correctly
    Mocktest

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Step 5: Use the Custom Tool in the Agent

After creating and testing your tool actions, you must add them to your agent. This allows the agent to call the tool during conversations and perform real-world operations.

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Steps:

  1. Open the Agent Builder
  2. Click Add Tool/Function Calls
  3. Click App Tool Call
  4. Select the tool/app you created or configured
  5. Select the action you want the agent to use
  6. Click Submit
    Toolaction 1

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Example Agent Workflow

  1. User: I want to reschedule my appointment
  2. Agent collects the required information
  3. Agent calls Reschedule Booking action
  4. API processes the request
  5. Agent confirms the reschedule
Tool not triggering: Ensure the tool is enabled, and variables match exactlyAuthentication failing: Verify credentials and authentication typeAPI request failing: Test API action and verify endpoint and headers

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Best Practices

  • Always follow the API documentation of the external app
  • Use clear variable names
  • Test actions before enabling
  • Configure authentication properly
  • Use descriptive action names