Overview

The Define Tool node creates tool definitions that enable LLMs to interact with external functions, APIs, and services. Each node defines a single tool with its JSON schema and Python implementation code. Multiple Define Tool nodes can be chained together to build a comprehensive toolkit for the Call LLM with Tools node.

A key architectural feature of HyperFlow is its canonical tool definition format - a universal schema that works across all LLM providers. You define tools once using HyperFlow's standard format, and the system automatically translates these definitions into the specific formats required by each LLM service (OpenAI's function calling, Anthropic's tool use, Google's function declarations, etc.). This ensures true portability and eliminates the need to rewrite tool definitions when switching between LLM providers.

Node Specification

Core Properties

Parameters

Input Ports

Output Ports

Process Flow Exits

Tool Definition Schema

Important: This is HyperFlow's canonical tool definition format - a fixed schema that must be followed exactly. HyperFlow automatically converts this universal format into the specific schemas required by each LLM service (OpenAI, Anthropic, Google, etc.), ensuring your tool definitions work seamlessly across all supported LLM providers without modification.

The JSON tool definition follows this structure:

{
  "name": "tool_name",
  "description": "Clear description of what the tool does",
  "parameters": {
    "param1": {
      "type": "string",
      "description": "Parameter description",
      "required": true
    },
    "param2": {
      "type": "number",
      "description": "Optional parameter",
      "required": false
    }
  },
  "return_value": {
    "type": "object"
  },
  "tool_call": {
    "tool": "tool_name",
    "parameters": {
      "param1": "<value>"
    }
  },
  "examples": [
    {
      "user_input": "Example query",
      "tool_call": {
        "tool": "tool_name",
        "parameters": {
          "param1": "example_value"
        }
      },
      "expected_output": {
        "result": "example output"
      }
    }
  ]
}

Schema Fields