Example 7: Tool Integration

The final tutorial example demonstrates external tool integration—calling APIs during workflow execution and controlling which tools are available at each step.

Objective

In this example, you’ll learn:

How to use the call action to invoke external tools
How to use tools.allow for progressive tool disclosure
How to use tools.call to force tool execution
How to integrate external validation requests and notifications into your workflow

The Scenario

Your contact form needs to integrate with external systems:

Request email-domain validation using an external API
Send a notification to CRM when the form is completed
Restrict tool access during sensitive data collection steps

This creates a production-ready workflow with real integrations.

Implementation

Here’s the complete tool definition:

{
  "type": "context",
  "context": {
    "task": {
      "type": "steps",
      "version": "v1alpha",
      "id": "contact-form-with-integration",
      "tool": {
        "name": "submit_contact_info",
        "description": "Submit contact form information with external integrations"
      },
      "steps": [
        {
          "id": "COLLECT_NAME",
          "goal": "Collect the user's name",
          "instructions": [
            "Ask the user for their name.",
            "Once you have their name, call the submit_contact_info tool with the user_name parameter."
          ],
          "inputs": [
            {
              "name": "user_name",
              "type": "string",
              "description": "The user's name",
              "required": true
            }
          ],
          "tools": {
            "allow": ["submit_contact_info"]
          },
          "on": {
            "enter": [
              {"action": "say", "text": "Welcome! Let's collect your contact information."}
            ],
            "submit": [
              {"action": "save"}
            ]
          },
          "next": [{"id": "COLLECT_EMAIL"}]
        },
        {
          "id": "COLLECT_EMAIL",
          "goal": "Collect and validate the user's email address",
          "instructions": [
            "Ask the user for their email address.",
            "Once you have their email, call the submit_contact_info tool with the user_email parameter.",
            "The system will validate the email domain automatically."
          ],
          "inputs": [
            {
              "name": "user_email",
              "type": "string",
              "description": "The user's email address",
              "required": true
            }
          ],
          "tools": {
            "allow": ["submit_contact_info", "validate_email_domain"]
          },
          "on": {
            "submit": [
              {
                "action": "call",
                "name": "validate_email_domain",
                "arguments": {
                  "email": "{{inputs.user_email}}"
                }
              },
              {"action": "save"}
            ]
          },
          "next": [{"id": "COLLECT_TIME"}]
        },
        {
          "id": "COLLECT_TIME",
          "goal": "Collect the user's preferred contact time",
          "instructions": [
            "Ask the user for their preferred contact time.",
            "Once you have their preference, call the submit_contact_info tool with the contact_time parameter."
          ],
          "inputs": [
            {
              "name": "contact_time",
              "type": "string",
              "description": "The user's preferred contact time",
              "required": true,
              "enum": ["morning", "afternoon", "evening", "night"]
            }
          ],
          "tools": {
            "allow": ["submit_contact_info"]
          },
          "on": {
            "submit": [
              {"action": "save"}
            ]
          },
          "next": [{"id": "CONFIRM_AND_NOTIFY"}]
        },
        {
          "id": "CONFIRM_AND_NOTIFY",
          "goal": "Confirm information and send CRM notification",
          "instructions": [
            "Summarize the collected information for the user:",
            "- Name: {{user_name}}",
            "- Email: {{user_email}}",
            "- Preferred contact time: {{contact_time}}",
            "Ask them to confirm, then call the submit_contact_info tool to complete."
          ],
          "inputs": [],
          "tools": {
            "allow": ["submit_contact_info", "send_crm_notification"],
            "call": true
          },
          "on": {
            "enter": [
              {
                "action": "call",
                "name": "send_crm_notification",
                "arguments": {
                  "name": "{{user_name}}",
                  "email": "{{user_email}}",
                  "contact_time": "{{contact_time}}",
                  "source": "contact_form_workflow"
                }
              }
            ]
          }
        }
      ]
    }
  },
  "tool": {
    "type": "function",
    "function": {
      "name": "contact_form_integration_workflow",
      "description": "Multi-step workflow with external tool integration",
      "parameters": {
        "type": "object",
        "properties": {},
        "required": []
      }
    }
  }
}

Key Concepts

The `call` Action

The call action invokes an external tool from a lifecycle hook. Cortex automatically decides the routing path based on whether the arguments supply all of the target tool’s required parameters:

{
  "action": "call",
  "name": "validate_email_domain",
  "arguments": {
    "email": "{{inputs.user_email}}"
  }
}

Auto-decide routing:

Required params supplied?	Route	What happens
All present (or tool has none)	Inject (synthetic)	Tool call bypasses the LLM and executes in a single turn.
Some missing	Hint (LLM-guided)	A `pending_tool_call` is queued; the LLM generates the call on the next turn with forced `tool_choice`.

In the COLLECT_EMAIL example above, validate_email_domain requires one param (email) and arguments provides it via template — so Cortex takes the inject route: the tool executes synthetically without LLM involvement. If you omitted the email key from arguments, Cortex would take the hint route: the LLM would see a pending_tool_call hint and generate the call itself. Important: The workflow engine does not automatically copy external tool results into inputs.* or local.*. If later routing depends on a tool result, add a follow-up submit step that captures normalized result fields, or rely on endpoint-persisted vars.*. Template variables in arguments:

{{inputs.user_email}} — Current step input
{{user_name}} — Global variable (saved from earlier step)
{{local.counter}} — Task-local variable

Progressive Tool Disclosure with `tools.allow`

Control which tools are visible at each step:

// COLLECT_NAME: Only submit tool (no external tools needed)
"tools": {
  "allow": ["submit_contact_info"]
}

// COLLECT_EMAIL: Submit + email validation tool
"tools": {
  "allow": ["submit_contact_info", "validate_email_domain"]
}

// CONFIRM_AND_NOTIFY: Submit + CRM notification tool
"tools": {
  "allow": ["submit_contact_info", "send_crm_notification"]
}

Benefits:

Security: Prevent access to sensitive tools during early steps
Focus: Agent only sees relevant tools for the current task
Progressive disclosure: Unlock capabilities as the workflow advances

Note: The submit tool is always available, regardless of tools.allow.

Auto-Advancing with `tools.call`

tools.call: true forces the LLM to produce a tool call on turns where no pending call action exists. In practice, this forces the submit tool — making it the standard mechanism for auto-advancing bridge steps. tools.call and call actions operate on different turns and compose naturally:

{
  "id": "CONFIRM_AND_NOTIFY",
  "tools": {
    "allow": ["submit_contact_info", "send_crm_notification"],
    "call": true
  },
  "on": {
    "enter": [
      {"action": "call", "name": "send_crm_notification", "arguments": {...}}
    ]
  }
}

What happens:

Step is entered, on.enter fires the call action
send_crm_notification has all required params provided → inject route: tool executes synthetically (single turn)
On the next turn, no pending call remains → tools.call: true forces the submit tool
The step submits and the workflow advances

If the call action took the hint route instead (missing required params), the sequence would be: turn 1 queues the hint → turn 2 the LLM generates the tool call (forced tool_choice) → turn 3 tools.call: true forces submit. Use cases for tools.call: true:

Auto-advancing bridge steps after a call action completes
Forcing submit on terminal steps with no inputs
Making zero-input steps fully deterministic

External Tool Assumptions

This example assumes two external tools are available: 1. validate_email_domain

{
  "name": "validate_email_domain",
  "description": "Validates that an email domain exists and accepts mail",
  "parameters": {
    "properties": {
      "email": {"type": "string", "description": "Email to validate"}
    },
    "required": ["email"]
  }
}

Returns: {"valid": true/false, "domain": "example.com", "message": "..."} 2. send_crm_notification

{
  "name": "send_crm_notification",
  "description": "Sends a lead notification to the CRM system",
  "parameters": {
    "properties": {
      "name": {"type": "string"},
      "email": {"type": "string"},
      "contact_time": {"type": "string"},
      "source": {"type": "string"}
    },
    "required": ["name", "email"]
  }
}

Returns: {"success": true, "lead_id": "12345"}

How It Works

Step-by-Step Flow

User: "Hello"

[Platform enters COLLECT_NAME]
  → tools.allow: only submit_contact_info visible
  → on.enter: say "Welcome!"

Agent: "Welcome! Let's collect your contact information. What is your name?"

User: "Alice"

[Agent calls submit_contact_info(user_name="Alice")]
  → on.submit: save user_name
  → Transition to COLLECT_EMAIL
  → tools.allow: submit + validate_email_domain visible

Agent: "What is your email address?"

User: "alice@example.com"

[Agent calls submit_contact_info(user_email="alice@example.com")]
  → on.submit: call validate_email_domain(email="alice@example.com")
  → Required param "email" provided → inject route (synthetic, single turn)
  → Tool executes, response available to the agent
  → on.submit: save user_email
  → Transition to COLLECT_TIME

Agent: "Thanks. What is your preferred contact time?"

User: "morning"

[Agent calls submit_contact_info(contact_time="morning")]
  → on.submit: save contact_time
  → Transition to CONFIRM_AND_NOTIFY
  → on.enter: call send_crm_notification(...)
  → All required params provided → inject route (synthetic, single turn)
  → CRM receives notification
  → Next turn: no pending call → tools.call: true forces submit

Agent: "I've recorded your information and notified our team. Here's what we have:
- Name: Alice
- Email: alice@example.com
- Preferred contact time: morning

Is this correct?"

User: "Yes"

[Agent calls submit_contact_info()]
  → No next step (terminal)
  → Workflow completes

Agent: "Thank you! We'll be in touch soon."

Tool Visibility Per Step

Step	Available Tools
COLLECT_NAME	`submit_contact_info`
COLLECT_EMAIL	`submit_contact_info`, `validate_email_domain`
COLLECT_TIME	`submit_contact_info`
CONFIRM_AND_NOTIFY	`submit_contact_info`, `send_crm_notification`

Best Practices

1. Minimize Tool Access

Only expose tools that are needed for the current step:

// Good: Restricted to what's needed
"tools": {"allow": ["submit_contact_info", "lookup_patient"]}

// Avoid: All tools visible when only one is needed
"tools": {}  // null = all tools

2. Use `call` for Mandatory Operations

When a tool must be called (validation, notification), use the call action:

"on": {
  "submit": [
    {"action": "call", "name": "log_audit_event", "arguments": {...}}
  ]
}

3. Combine `tools.call` with `on.enter` for Data Fetching

When you need data before the step can proceed:

{
  "id": "SHOW_ACCOUNT_BALANCE",
  "tools": {"call": true},
  "on": {
    "enter": [
      {"action": "call", "name": "get_account_balance", "arguments": {"id": "{{account_id}}"}}
    ]
  }
}

4. Handle Tool Failures Gracefully

External tools can fail. Consider adding error handling steps:

"next": [
  {"if": "local.validation_passed", "id": "NEXT_STEP"},
  {"if": "local.validation_failed", "id": "HANDLE_ERROR"},
  {"id": "RETRY"}
]

5. Normalize Tool Results Before Branching

If a future step needs structured data from an external tool, do not assume the result is automatically written into workflow state. Instead:

queue the external tool call,
let the agent read the tool result,
have the agent resubmit normalized fields such as validation_status or directory_name,
branch only on inputs.*, local.*, or known vars.*.

Try It

To test this workflow, you’ll need:

The workflow JSON above assigned to an agent
External tools (validate_email_domain, send_crm_notification) available in your environment

Note: If external tools aren’t available, you can modify the example to remove the call actions and test the tools.allow behavior independently.

Summary

Congratulations! You’ve completed the Step Workflows tutorial. You now know how to:

Create basic workflows with steps and terminal states (Example 1)
Collect and validate inputs with automatic schema generation (Example 2)
Chain multiple steps with transitions and data persistence (Example 3)
Add polish with lifecycle actions, say messages, and counters (Example 4)
Route conditionally based on user input (Example 5)
Handle validation failures with retry loops (Example 6)
Integrate external tools with progressive disclosure (Example 7)

For complete reference documentation, see Step Workflow Reference.

Introduction to Syllable

Tutorials

Account

Workspaces

Resources

Example 7: Tool Integration

Objective

The Scenario

Implementation

Key Concepts

The `call` Action

Progressive Tool Disclosure with `tools.allow`

Auto-Advancing with `tools.call`

External Tool Assumptions

How It Works

Step-by-Step Flow

Tool Visibility Per Step

Best Practices

1. Minimize Tool Access

2. Use `call` for Mandatory Operations

3. Combine `tools.call` with `on.enter` for Data Fetching

4. Handle Tool Failures Gracefully

5. Normalize Tool Results Before Branching

Try It

Summary

Introduction to Syllable

Tutorials

Account

Workspaces

Resources

Documentation Index

​Objective

​The Scenario

​Implementation

​Key Concepts

​The call Action

​Progressive Tool Disclosure with tools.allow

​Auto-Advancing with tools.call

​External Tool Assumptions

​How It Works

​Step-by-Step Flow

​Tool Visibility Per Step

​Best Practices

​1. Minimize Tool Access

​2. Use call for Mandatory Operations

​3. Combine tools.call with on.enter for Data Fetching

​4. Handle Tool Failures Gracefully

​5. Normalize Tool Results Before Branching

​Try It

​Summary

Objective

The Scenario

Implementation

Key Concepts

The `call` Action

Progressive Tool Disclosure with `tools.allow`

Auto-Advancing with `tools.call`

External Tool Assumptions

How It Works

Step-by-Step Flow

Tool Visibility Per Step

Best Practices

1. Minimize Tool Access

2. Use `call` for Mandatory Operations

3. Combine `tools.call` with `on.enter` for Data Fetching

4. Handle Tool Failures Gracefully

5. Normalize Tool Results Before Branching

Try It

Summary