Function Calling - Portkey Docs

Functions Usage

Portkey supports the OpenAI signature to define functions. Pass the tools parameter to models that support function/tool calling.

NodeJS
Python
OpenAI NodeJS
OpenAI Python
cURL

import Portkey from 'portkey-ai';

const portkey = new Portkey({
    apiKey: "PORTKEY_API_KEY",
});

async function run() {
  const response = await portkey.chat.completions.create({
    model: "MODEL_NAME",
    messages: [{ role: "user", content: "What's the weather like in Boston today?" }],
    tools: [{
        type: "function",
        function: {
          name: "get_current_weather",
          description: "Get the current weather in a given location",
          parameters: {
            type: "object",
            properties: {
              location: {
                type: "string",
                description: "The city and state, e.g. San Francisco, CA",
              },
              unit: { type: "string", enum: ["celsius", "fahrenheit"] },
            },
            required: ["location"],
          },
        }
    }],
    tool_choice: "auto",
  });

  console.log(response.choices[0].message.tool_calls);
}

run();

from portkey_ai import Portkey

portkey = Portkey(
    api_key="PORTKEY_API_KEY",
)

completion = portkey.chat.completions.create(
  model="MODEL_NAME",
  messages=[{"role": "user", "content": "What's the weather like in Boston today?"}],
  tools=[{
    "type": "function",
    "function": {
      "name": "get_current_weather",
      "description": "Get the current weather in a given location",
      "parameters": {
        "type": "object",
        "properties": {
          "location": {
            "type": "string",
            "description": "The city and state, e.g. San Francisco, CA",
          },
          "unit": {"type": "string", "enum": ["celsius", "fahrenheit"]},
        },
        "required": ["location"],
      },
    }
  }],
  tool_choice="auto"
)

print(completion.choices[0].message.tool_calls)

import OpenAI from 'openai';
import { PORTKEY_GATEWAY_URL, createHeaders } from 'portkey-ai'

const openai = new OpenAI({
  baseURL: PORTKEY_GATEWAY_URL,
  defaultHeaders: createHeaders({
    apiKey: "PORTKEY_API_KEY"
  })
});

async function run() {
  const response = await openai.chat.completions.create({
    model: "MODEL_NAME",
    messages: [{ role: "user", content: "What's the weather like in Boston today?" }],
    tools: [{
        type: "function",
        function: {
          name: "get_current_weather",
          description: "Get the current weather in a given location",
          parameters: {
            type: "object",
            properties: {
              location: {
                type: "string",
                description: "The city and state, e.g. San Francisco, CA",
              },
              unit: { type: "string", enum: ["celsius", "fahrenheit"] },
            },
            required: ["location"],
          },
        }
    }],
    tool_choice: "auto",
  });

  console.log(response.choices[0].message.tool_calls);
}

run();

from openai import OpenAI
from portkey_ai import PORTKEY_GATEWAY_URL, createHeaders

openai = OpenAI(
    base_url=PORTKEY_GATEWAY_URL,
    default_headers=createHeaders(
        api_key="PORTKEY_API_KEY"
    )
)

completion = openai.chat.completions.create(
  model="MODEL_NAME",
  messages=[{"role": "user", "content": "What's the weather like in Boston today?"}],
  tools=[{
    "type": "function",
    "function": {
      "name": "get_current_weather",
      "description": "Get the current weather in a given location",
      "parameters": {
        "type": "object",
        "properties": {
          "location": {
            "type": "string",
            "description": "The city and state, e.g. San Francisco, CA",
          },
          "unit": {"type": "string", "enum": ["celsius", "fahrenheit"]},
        },
        "required": ["location"],
      },
    }
  }],
  tool_choice="auto"
)

print(completion.choices[0].message.tool_calls)

curl "https://api.portkey.ai/v1/chat/completions" \
  -H "Content-Type: application/json" \
  -H "x-portkey-api-key: $PORTKEY_API_KEY" \
  -d '{
  "model": "MODEL_NAME",
  "messages": [
    {
      "role": "user",
      "content": "What is the weather like in Boston?"
    }
  ],
  "tools": [
    {
      "type": "function",
      "function": {
        "name": "get_current_weather",
        "description": "Get the current weather in a given location",
        "parameters": {
          "type": "object",
          "properties": {
            "location": {
              "type": "string",
              "description": "The city and state, e.g. San Francisco, CA"
            },
            "unit": {
              "type": "string",
              "enum": ["celsius", "fahrenheit"]
            }
          },
          "required": ["location"]
        }
      }
    }
  ],
  "tool_choice": "auto"
}'

API Reference

On completion, the request logs in the Portkey UI where tools and functions are visible. Portkey automatically formats the JSON blocks in the input and output for easier debugging.

Managing Functions and Tools in Prompts

Create prompt templates with function/tool definitions in Portkey’s Prompt Library. Set the tool_choice parameter, and Portkey validates your tool definition on the fly, eliminating syntax errors.

Supported Providers and Models

Portkey provides native function calling support across all major AI providers. If you discover a function-calling capable LLM that isn’t working with Portkey, please let us know on Discord.

Cookbook

See the detailed cookbook on function calling.

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Last modified on August 3, 2026