tool

function tool<TInput, TReturn>(config): InvokableTool<ZodInferred<TInput>, TReturn>;

Defined in: src/tools/zod-tool.ts:234

Creates an InvokableTool from a Zod schema and callback function.

The tool() function validates input against the schema and generates JSON schema for model providers using Zod v4’s built-in z.toJSONSchema() method.

Type Parameters

Type Parameter	Default type	Description
TInput extends ZodType<unknown, unknown, $ZodTypeInternals<unknown, unknown>>	-	Zod schema type for input validation
TReturn extends JSONValue	JSONValue	Return type of the callback function

Parameters

Parameter	Type	Description
config	ToolConfig<TInput, TReturn>	Tool configuration

Returns

InvokableTool<ZodInferred<TInput>, TReturn>

An InvokableTool that implements the Tool interface with invoke() method

Example

import { tool } from '@strands-agents/sdk'
import { z } from 'zod'

// Tool with input parameters
const calculator = tool({
  name: 'calculator',
  description: 'Performs basic arithmetic',
  inputSchema: z.object({
    operation: z.enum(['add', 'subtract', 'multiply', 'divide']),
    a: z.number(),
    b: z.number()
  }),
  callback: (input) => {
    switch (input.operation) {
      case 'add': return input.a + input.b
      case 'subtract': return input.a - input.b
      case 'multiply': return input.a * input.b
      case 'divide': return input.a / input.b
    }
  }
})

// Tool without input (omit inputSchema)
const getStatus = tool({
  name: 'getStatus',
  description: 'Gets system status',
  callback: () => ({ status: 'operational', uptime: 99.9 })
})

// Direct invocation
const result = await calculator.invoke({ operation: 'add', a: 5, b: 3 })

// Agent usage
for await (const event of calculator.stream(context)) {
  console.log(event)
}