Tool as a step

Workflows can include tools as steps. This example shows how to define an tool as a step using createStep().

Creating a tool

Create a simple tool that takes a string input and returns the reversed version.

src/mastra/tools/example-reverse-tool.ts


import { createTool } from "@mastra/core/tools";
import { z } from "zod";
 
export const reverseTool = createTool({
  id: "reverse-tool",
  description: "Reverse the input string",
  inputSchema: z.object({
    input: z.string()
  }),
  outputSchema: z.object({
    output: z.string()
  }),
  execute: async ({ context }) => {
    const { input } = context;
    const reversed = input.split("").reverse().join("");
 
    return {
      output: reversed
    };
  }
});

Tool as step

Use a tool as a step by passing it directly to createStep(). Using .map() is optional because tools define their own input and output schemas, but can be helpful when the workflow inputSchema doesn’t match the tool’s inputSchema.

In this example, the workflow accepts a word, which is mapped to the tool’s input. The tool returns an output string, which is passed directly to the workflow’s reversed output without any extra transformation.

src/mastra/workflows/example-tool-step.ts


import { createWorkflow, createStep } from "@mastra/core/workflows";
import { z } from "zod";
 
import { reverseTool } from "../tools/example-reverse-tool";
 
const step1 = createStep(reverseTool);
 
export const toolAsStep = createWorkflow({
  id: "tool-step-workflow",
  inputSchema: z.object({
    word: z.string()
  }),
  outputSchema: z.object({
    reversed: z.string()
  })
})
  .map(async ({ inputData }) => {
    const { word } = inputData;
 
    return {
      input: word
    };
  })
  .then(step1)
  .commit();

Workflows (Legacy)

The following links provide example documentation for legacy workflows: