---
title: "Skills Format Specification | Tajo"
description: "Learn the skills.md format for defining AI-powered automation skills that integrate with Brevo."
url: https://tajo.io/docs/skills/overview/skills-format/
markdown: https://tajo.io/docs/skills/overview/skills-format.md
lang: en-US
author: "Set Noa"
author_url: https://tajo.io/set-noa/
---

# Skills Format Specification

[Set Noa](https://tajo.io/set-noa/)

The **skills.md** format defines how Skills are structured, configured, and executed. This specification ensures consistent behavior across all Tajo Skills.

## File Structure

A skill is defined in a single markdown file with YAML frontmatter:

```markdown
---
name: customer-sync
version: 2.1.0
description: Sync customer data to Brevo contacts
category: data-sync
status: stable

triggers:
  - event: customer_created
  - event: customer_updated
  - event: customer_deleted

actions:
  - brevo/create-contact
  - brevo/update-contact
  - brevo/delete-contact

brevoEndpoints:
  - POST /v3/contacts
  - PUT /v3/contacts/{identifier}
  - DELETE /v3/contacts/{identifier}

permissions:
  - contacts:write
  - contacts:read
---

# Customer Sync

Automatically synchronize customer data from your platform to Brevo contacts.

## Overview

This skill listens for customer lifecycle events and mirrors changes to Brevo...
```

## Frontmatter Fields

### Required Fields

| Field | Type | Description |
| --- | --- | --- |
| `name` | string | Unique identifier (kebab-case) |
| `version` | string | Semantic version (e.g., “2.1.0”) |
| `description` | string | Short description (max 160 chars) |
| `category` | enum | One of: `data-sync`, `email-marketing`, `sms-whatsapp`, `loyalty`, `analytics`, `integrations` |
| `triggers` | array | Events that activate this skill |
| `actions` | array | Operations this skill can perform |

### Optional Fields

| Field | Type | Default | Description |
| --- | --- | --- | --- |
| `status` | enum | `stable` | One of: `stable`, `beta`, `experimental` |
| `brevoEndpoints` | array | `[]` | Brevo API endpoints used |
| `permissions` | array | `[]` | Required Brevo API permissions |
| `relatedSkills` | array | `[]` | IDs of related skills |
| `featured` | boolean | `false` | Highlight in skill catalog |

## Triggers

Triggers define what events activate the skill.

### Event Triggers

```yaml
triggers:
  - event: cart_abandoned
    conditions:
      - cart_value: "> 50"        # Minimum cart value
      - items_count: ">= 1"       # At least one item
      - time_since_activity: "> 30m"  # 30 minutes of inactivity
    debounce: 5m                  # Wait 5 minutes before re-triggering
```

### Schedule Triggers

```yaml
triggers:
  - schedule: "0 9 * * *"         # Cron expression (daily at 9am)
    timezone: "America/New_York"
  - schedule: every_hour
  - schedule: every_day
```

### Webhook Triggers

```yaml
triggers:
  - webhook: /skills/customer-sync/trigger
    method: POST
    authentication: api_key
```

### Condition Operators

| Operator | Description | Example |
| --- | --- | --- |
| `=` | Equals | `status: "active"` |
| `!=` | Not equals | `status: "!= deleted"` |
| `>` | Greater than | `cart_value: "> 50"` |
| `>=` | Greater than or equal | `items: ">= 1"` |
| `<` | Less than | `age: "< 30"` |
| `<=` | Less than or equal | `quantity: "<= 10"` |
| `contains` | String contains | `email: "contains @gmail.com"` |
| `starts_with` | String prefix | `name: "starts_with Dr."` |
| `in` | Value in list | `country: "in US,CA,UK"` |

## Actions

Actions define what operations the skill performs.

### Action Definition

```yaml
actions:
  - id: send_reminder_email
    type: brevo/send-email
    parameters:
      template_id: 12345
      to: "{{ contact.email }}"
      params:
        first_name: "{{ contact.firstName }}"
        cart_items: "{{ cart.items }}"
    retry:
      attempts: 3
      backoff: exponential
    on_error: continue  # or 'stop'
```

### Action Types

| Type | Description |
| --- | --- |
| `brevo/send-email` | Send transactional email |
| `brevo/send-sms` | Send SMS message |
| `brevo/send-whatsapp` | Send WhatsApp message |
| `brevo/create-contact` | Create new contact |
| `brevo/update-contact` | Update contact attributes |
| `brevo/delete-contact` | Delete contact |
| `brevo/add-to-list` | Add contact to list |
| `brevo/remove-from-list` | Remove contact from list |
| `brevo/track-event` | Track custom event |
| `http/request` | Make HTTP request |
| `transform/map` | Transform data |
| `control/delay` | Wait before continuing |
| `control/condition` | Branch based on condition |

### Template Variables

Use `{{ }}` syntax to reference data:

```yaml
parameters:
  to: "{{ contact.email }}"
  subject: "Your order #{{ order.number }} has shipped"
  params:
    name: "{{ contact.firstName | default: 'Customer' }}"
    items: "{{ cart.items | map: 'name' | join: ', ' }}"
    total: "{{ cart.total | currency: 'USD' }}"
```

### Available Filters

| Filter | Description | Example |
| --- | --- | --- |
| `default` | Default value | `{{ name \| default: 'Guest' }}` |
| `uppercase` | Uppercase string | `{{ name \| uppercase }}` |
| `lowercase` | Lowercase string | `{{ email \| lowercase }}` |
| `capitalize` | Capitalize first letter | `{{ name \| capitalize }}` |
| `truncate` | Truncate string | `{{ desc \| truncate: 100 }}` |
| `date` | Format date | `{{ date \| date: 'YYYY-MM-DD' }}` |
| `currency` | Format currency | `{{ price \| currency: 'EUR' }}` |
| `map` | Map array property | `{{ items \| map: 'name' }}` |
| `join` | Join array | `{{ tags \| join: ', ' }}` |
| `first` | First array item | `{{ items \| first }}` |
| `last` | Last array item | `{{ items \| last }}` |
| `size` | Array/string length | `{{ items \| size }}` |

## Permissions

Define required Brevo API permissions:

```yaml
permissions:
  - contacts:read        # Read contact data
  - contacts:write       # Create/update contacts
  - email:send           # Send transactional emails
  - sms:send             # Send SMS messages
  - lists:write          # Manage contact lists
  - events:write         # Track events
```

## Complete Example

```yaml
---
name: abandoned-cart-recovery
version: 3.0.0
description: Recover abandoned shopping carts with a multi-step email sequence
category: email-marketing
status: stable

triggers:
  - event: cart_abandoned
    conditions:
      - cart_value: "> 25"
      - customer_email: "exists"
      - items_count: ">= 1"
    debounce: 30m

actions:
  - id: wait_1h
    type: control/delay
    parameters:
      duration: 1h

  - id: check_purchase
    type: control/condition
    parameters:
      condition: "{{ cart.converted }} = false"
      then: send_first_email
      else: stop

  - id: send_first_email
    type: brevo/send-email
    parameters:
      template_id: {{ env.ABANDONED_CART_TEMPLATE_1 }}
      to: "{{ contact.email }}"
      params:
        first_name: "{{ contact.firstName }}"
        cart_url: "{{ cart.recovery_url }}"
        items: "{{ cart.items }}"
        total: "{{ cart.total | currency }}"

  - id: wait_24h
    type: control/delay
    parameters:
      duration: 24h

  - id: check_purchase_2
    type: control/condition
    parameters:
      condition: "{{ cart.converted }} = false"
      then: send_second_email
      else: stop

  - id: send_second_email
    type: brevo/send-email
    parameters:
      template_id: {{ env.ABANDONED_CART_TEMPLATE_2 }}
      to: "{{ contact.email }}"
      params:
        first_name: "{{ contact.firstName }}"
        cart_url: "{{ cart.recovery_url }}"
        discount_code: "{{ generate_discount(10, 'percent') }}"

brevoEndpoints:
  - POST /v3/smtp/email
  - GET /v3/contacts/{identifier}

permissions:
  - contacts:read
  - email:send

relatedSkills:
  - customer-sync
  - order-events
  - browse-abandonment
---

# Abandoned Cart Recovery

Recover lost sales with a proven multi-step email sequence...
```

## MCP Tool Exposure

Skills can be exposed as MCP tools, making them callable by AI agents. Add the `mcp` field to your frontmatter:

```yaml
---
name: abandoned-cart-recovery
version: 3.0.0
description: Recover abandoned shopping carts with a multi-step email sequence
category: email-marketing

# MCP Configuration
mcp:
  tool_name: tajo/recover-abandoned-cart
  description: Execute abandoned cart recovery sequence for a specific cart
  inputSchema:
    type: object
    properties:
      cart_id:
        type: string
        description: The abandoned cart identifier
      customer_email:
        type: string
        description: Customer email address
      min_cart_value:
        type: number
        description: Minimum cart value to trigger recovery
        default: 25
    required: [cart_id, customer_email]
  brevo_servers:
    - brevo_contacts
    - brevo_email_campaign_management
    - brevo_templates
---
```

### How MCP Exposure Works

When a skill has an `mcp` field, it becomes a tool that AI agents can discover and invoke:

```
Agent: "Recover abandoned cart #4521 for user@example.com"
    ↓
MCP Tool Discovery: finds tajo/recover-abandoned-cart
    ↓
Tool Execution: runs the skill's action chain
    ↓
Brevo MCP Servers: contacts + email modules called
    ↓
Result: recovery sequence initiated
```

### MCP Fields

| Field | Type | Description |
| --- | --- | --- |
| `mcp.tool_name` | string | MCP tool name (format: `tajo/skill-name`) |
| `mcp.description` | string | Description shown to AI agents during tool discovery |
| `mcp.inputSchema` | object | JSON Schema defining the tool’s input parameters |
| `mcp.brevo_servers` | array | Which Brevo MCP server modules this skill needs |

### Skills vs Direct MCP Tools

| Aspect | Skill as MCP Tool | Direct Brevo MCP |
| --- | --- | --- |
| **Abstraction** | High, agent says “recover this cart” | Low, agent must call individual Brevo endpoints |
| **Complexity** | Encapsulates multi-step logic | Agent must orchestrate each step |
| **Guardrails** | Built into the skill (conditions, debounce) | Agent must implement its own |
| **Best for** | Repeatable workflows | Ad-hoc operations |

Tip

**Use Skills as MCP tools** for complex, multi-step workflows that agents shouldn’t reinvent each time. Use **direct Brevo MCP tools** for simple, one-off operations like looking up a contact or sending a single email.

### Composing Skills and Agents

An agent can use both Skills (as MCP tools) and direct Brevo MCP modules:

```yaml
# Agent spec
---
name: retention-agent
tools:
  # Tajo Skills as MCP tools
  - tajo/recover-abandoned-cart
  - tajo/customer-sync
  - tajo/win-back-sequence
  # Direct Brevo MCP modules
  - brevo_contacts
  - brevo_campaign_analytics
  - brevo_segments
---
```

This gives agents high-level automation (Skills) for common patterns while retaining low-level access (Brevo MCP) for custom logic.

See [Agent Specification Format](https://tajo.io/docs/mcp/agent-specification) and [Building Agents](https://tajo.io/docs/mcp/building-agents) for full details.

## Best Practices

Tip

**Version your skills** using semantic versioning. Breaking changes require a major version bump.

1. **Keep skills focused** - One skill should do one thing well
2. **Use descriptive names** - `abandoned-cart-recovery` not `acr`
3. **Document conditions** - Explain why each condition exists
4. **Handle errors gracefully** - Use `on_error: continue` for non-critical actions
5. **Test with small audiences** - Use `status: experimental` during development
6. **Add MCP exposure** for skills that agents should be able to invoke directly

## Next Steps

- [MCP & Agents Overview](https://tajo.io/docs/mcp) - How Skills fit into the agentic architecture
- [Agent Specification Format](https://tajo.io/docs/mcp/agent-specification) - Define agents that use Skills as tools
- [Building Agents](https://tajo.io/docs/mcp/building-agents) - Build your first marketing agent
- [Data Sync Skills](https://tajo.io/docs/skills/data-sync) - Explore data synchronization skills