Examples

Practical function examples for business actions, API integrations, and lightweight code execution.

The fastest way to understand functions is to look at real patterns.

These examples show how teams typically use functions in production.

Example 1: Customer lookup with webhook mode

Use webhook mode when you already have a backend endpoint.

curl -X POST https://{instance}.{region}.everstack.ai/v1/functions \
  -H "Content-Type: application/json" \
  -d '{
    "name": "search_customers",
    "description": "Search customers by name, email, or account ID",
    "mode": "webhook",
    "parameters": {
      "type": "object",
      "properties": {
        "query": { "type": "string", "description": "Customer name, email, or ID" },
        "limit": { "type": "integer", "default": 5 }
      },
      "required": ["query"]
    },
    "webhook": {
      "url": "https://api.example.com/internal/search-customers",
      "method": "POST",
      "timeout_ms": 10000
    }
  }'

Best for:

support assistants
account lookup flows
CRM copilots

Example 2: Order history tool

This pattern works well when an agent needs to chain multiple functions together.

curl -X POST https://{instance}.{region}.everstack.ai/v1/functions \
  -H "Content-Type: application/json" \
  -d '{
    "name": "get_order_history",
    "description": "Get recent orders for a customer account",
    "mode": "webhook",
    "parameters": {
      "type": "object",
      "properties": {
        "account_id": { "type": "string" },
        "limit": { "type": "integer", "default": 10 }
      },
      "required": ["account_id"]
    },
    "webhook": {
      "url": "https://api.example.com/internal/orders",
      "method": "POST",
      "timeout_ms": 15000
    }
  }'

Pair this with search_customers so an agent can:

find the customer
extract the account ID
fetch recent orders
answer the user with live data

Example 3: Ticket creation for operations

Functions are often the cleanest way to turn operational actions into tools.

curl -X POST https://{instance}.{region}.everstack.ai/v1/functions \
  -H "Content-Type: application/json" \
  -d '{
    "name": "create_jira_ticket",
    "description": "Create a Jira issue for an operational incident",
    "mode": "webhook",
    "parameters": {
      "type": "object",
      "properties": {
        "summary": { "type": "string" },
        "description": { "type": "string" },
        "priority": { "type": "string", "enum": ["low", "medium", "high"] }
      },
      "required": ["summary", "description"]
    },
    "webhook": {
      "url": "https://ops.example.com/internal/create-jira-ticket",
      "method": "POST",
      "timeout_ms": 10000
    }
  }'

Best for:

incident response assistants
IT operations copilots
support escalation workflows

Example 4: Wrap an upstream API with proxy mode

Proxy mode works well when you want to put a cleaner contract in front of an API.

curl -X POST https://{instance}.{region}.everstack.ai/v1/functions \
  -H "Content-Type: application/json" \
  -d '{
    "name": "github_issue_lookup",
    "description": "Look up a GitHub issue by owner, repo, and issue number",
    "mode": "proxy",
    "parameters": {
      "type": "object",
      "properties": {
        "owner": { "type": "string" },
        "repo": { "type": "string" },
        "issue_number": { "type": "integer" }
      },
      "required": ["owner", "repo", "issue_number"]
    },
    "proxy": {
      "base_url": "https://api.github.com",
      "path": "/repos/{owner}/{repo}/issues/{issue_number}",
      "method": "GET"
    }
  }'

Best for:

standardizing external integrations
reducing custom integration glue
exposing limited parts of a large API

Example 5: Tax calculation with isolated mode

Use isolated mode when you need a small, bounded unit of custom logic.

curl -X POST https://{instance}.{region}.everstack.ai/v1/functions \
  -H "Content-Type: application/json" \
  -d '{
    "name": "calculate_tax",
    "description": "Calculate tax and total for an amount and rate",
    "mode": "isolated",
    "parameters": {
      "type": "object",
      "properties": {
        "amount": { "type": "number" },
        "rate": { "type": "number" }
      },
      "required": ["amount", "rate"]
    },
    "isolated": {
      "runtime": "nodejs20",
      "code": "export default async ({ amount, rate }) => ({ tax: amount * rate, total: amount * (1 + rate) })"
    },
    "timeout_ms": 30000,
    "memory_mb": 256
  }'

Best for:

pricing utilities
scoring logic
validation and formatting
custom transforms

Example 6: Normalize incoming data

Isolated functions are also good for cleanup or shaping work.

curl -X POST https://{instance}.{region}.everstack.ai/v1/functions \
  -H "Content-Type: application/json" \
  -d '{
    "name": "normalize_csv_row",
    "description": "Normalize a CSV row into a consistent record shape",
    "mode": "isolated",
    "parameters": {
      "type": "object",
      "properties": {
        "row": { "type": "object" }
      },
      "required": ["row"]
    },
    "isolated": {
      "runtime": "nodejs20",
      "code": "export default async ({ row }) => ({ email: String(row.email || '').trim().toLowerCase(), company: String(row.company || '').trim(), spend: Number(row.spend || 0) })"
    },
    "timeout_ms": 30000,
    "memory_mb": 256
  }'

Attach functions to an agent

Once functions are registered, add their names to an agent's tool list.

{
  "name": "support-assistant",
  "model": "claude-sonnet-4-20250514",
  "system_prompt": "Use the available tools to look up customer and order data before answering.",
  "tools": ["search_customers", "get_order_history", "create_jira_ticket"]
}

Example selection guide

start with webhook if you already own the backend
use proxy when you want a cleaner contract over an upstream API
use isolated when you need bounded custom logic without a full service

If you need a shell, files, or a long-running process, use a sandbox instead.

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