Tool calling

Tool calling lets a model invoke external functions. The model generates structured JSON arguments, your code executes the function, and the result goes back into the conversation.

How it works

Define tools as JSON schemas and pass them in the tools parameter.
The model may emit a tool_calls field instead of a text response.
Execute the function with the provided arguments.
Return the result as a tool message in the next request.

Example

curl -X POST https://api.radium.cloud/v1/chat/completions \\
  -H "Authorization: Bearer $RADIUM_API_KEY" \\
  -H "Content-Type: application/json" \\
  -d '{
    "model": "clarke-1.0",
    "messages": [{"role": "user", "content": "What is the weather in Toronto?"}],
    "tools": [{
      "type": "function",
      "function": {
        "name": "get_weather",
        "description": "Get current weather",
        "parameters": {
          "type": "object",
          "properties": {"location": {"type": "string"}},
          "required": ["location"]
        }
      }
    }]
  }'

from openai import OpenAI
client = OpenAI(api_key="YOUR_RADIUM_API_KEY", base_url="https://api.radium.cloud/v1")
response = client.chat.completions.create(
    model="clarke-1.0",
    messages=[{"role": "user", "content": "What is the weather in Toronto?"}],
    tools=[{
        "type": "function",
        "function": {
            "name": "get_weather",
            "description": "Get current weather",
            "parameters": {
                "type": "object",
                "properties": {"location": {"type": "string"}},
                "required": ["location"]
            }
        }
    }],
)
print(response.choices[0].message.tool_calls)

import OpenAI from "openai";
const client = new OpenAI({ apiKey: process.env.RADIUM_API_KEY, baseURL: "https://api.radium.cloud/v1" });
const response = await client.chat.completions.create({
  model: "clarke-1.0",
  messages: [{ role: "user", content: "What is the weather in Toronto?" }],
  tools: [{
    type: "function",
    function: {
      name: "get_weather",
      description: "Get current weather",
      parameters: {
        type: "object",
        properties: { location: { type: "string" } },
        required: ["location"]
      }
    }
  }],
});
console.log(response.choices[0].message.tool_calls);

Anthropic format

The same flow works in the Messages API. Tool definitions and response shapes match the Anthropic schema.

Model support matrix

Capability	hal-1.0	clarke-1.0	tycho-1.0
Single tool call	Pass	Pass	Pass
Multiple parallel calls	Pass	Pass	Pass
Multi-step tool loops	Pass	Pass	Limited
Streaming tool calls	Pass	Pass	Pass
Strict schema validation	Pass	Pass	Pass

Limitations

Parallel tool calls are supported; the model chooses whether to call one or multiple tools
For multi-step tool loops, inject the tool result back into the conversation as a tool message
Some niche OpenAI tool features (e.g., function_call: "none" behavior) may have minor differences

Getting started

Models

Switching

Core concepts

Tools

Guides

Enterprise

Tool calling

Tool calling

How it works

Example

Anthropic format

Model support matrix

Limitations

​Tool calling

​How it works

​Example

​Anthropic format

​Model support matrix

​Limitations

Tool calling

How it works

Example

Anthropic format

Model support matrix

Limitations