Tool Calling

await RunAnywhere.llm.tools.register(weatherTool, async (args) => ({
  tempC: await fetchTemp(String(args.city)),
}))

const result = await RunAnywhere.llm.generate('What is the weather in Lisbon?')

The tools namespace

RunAnywhere.llm.tools.register(tool: ToolDefinition, executor: ToolExecutor): Promise<void>
RunAnywhere.llm.tools.unregister(name: string): Promise<void>
RunAnywhere.llm.tools.list(): Promise<ToolDefinition[]>
RunAnywhere.llm.tools.clear(): Promise<void>

All four are async on React Native, unlike Web where they are synchronous.

Defining a tool

import type { ToolDefinition } from '@runanywhere/core'

const weatherTool: ToolDefinition = {
  name: 'get_weather',
  description: 'Get the current temperature for a city',
  parameters: [
    {
      name: 'city',
      type: 'string',
      description: 'City name',
      required: true,
    },
  ],
}

Controlling the loop

Field	Default	Meaning
`tools`	`[]`	Tools for this call only
`toolChoice`	`auto`	Whether the model may call a tool
`maxToolCalls`	`5`	Cap on calls in one exchange

const result = await RunAnywhere.llm.generate('Weather in Lisbon and Porto?', {
  toolChoice: 'auto',
  maxToolCalls: 3,
})

Tools registered through tools.register are offered to every generation. Tools passed in options.tools apply to that call alone. capabilities().tools reports { registry: true, parallel: false, cancellation: true }, so tools run one at a time but a run can be cancelled.

Executors run in JavaScript

Your executor is ordinary app code on the JS thread. It has fetch, storage, and native modules. It does not have the DOM. Keep it fast: the generation is paused while it runs, and a slow executor reads to the user as a hung model.

Removing

await RunAnywhere.llm.tools.unregister('get_weather')
await RunAnywhere.llm.tools.clear()

Inspecting

const registered = await RunAnywhere.llm.tools.list()

Which models can do this

Tool calling needs a model with enough context to hold the tool definitions. The SDK gates on context length rather than a model allowlist, so any model with a large enough window can participate, though instruction-tuned models trained on tool use do it far more reliably.

Getting Started

Swift SDK

Kotlin SDK

React Native SDK

Flutter SDK

Web SDK

Electron SDK

Vibe Coding

The tools namespace

Defining a tool

Controlling the loop

Executors run in JavaScript

Removing

Inspecting

Which models can do this

​The tools namespace

​Defining a tool

​Controlling the loop

​Executors run in JavaScript

​Removing

​Inspecting

​Which models can do this

The tools namespace

Defining a tool

Controlling the loop

Executors run in JavaScript

Removing

Inspecting

Which models can do this