How to integrate Workday MCP with Mastra AI

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Introduction

This guide walks you through connecting Workday to Mastra AI using the Composio tool router. By the end, you'll have a working Workday agent that can request vacation days for next week, check your current absence balance, find all open job postings i manage through natural language commands.

This guide will help you understand how to give your Mastra AI agent real control over a Workday account through Composio's Workday MCP server.

Before we dive in, let's take a quick look at the key ideas and tools involved.

Also integrate Workday with

TL;DR

Here's what you'll learn:
  • Set up your environment so Mastra, OpenAI, and Composio work together
  • Create a Tool Router session in Composio that exposes Workday tools
  • Connect Mastra's MCP client to the Composio generated MCP URL
  • Fetch Workday tool definitions and attach them as a toolset
  • Build a Mastra agent that can reason, call tools, and return structured results
  • Run an interactive CLI where you can chat with your Workday agent

What is Mastra AI?

Mastra AI is a TypeScript framework for building AI agents with tool support. It provides a clean API for creating agents that can use external services through MCP.

Key features include:

  • MCP Client: Built-in support for Model Context Protocol servers
  • Toolsets: Organize tools into logical groups
  • Step Callbacks: Monitor and debug agent execution
  • OpenAI Integration: Works with OpenAI models via @ai-sdk/openai

What is the Workday MCP server, and what's possible with it?

The Workday MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Workday account. It provides structured and secure access to your HR, payroll, and recruiting data, so your agent can perform actions like managing time off, retrieving employee details, tracking job postings, and analyzing interview feedback on your behalf.

  • Automated time off management: Easily create new time off requests or check absence balances for yourself or others, making leave management effortless.
  • Employee data and profile retrieval: Have your agent fetch profile details for the current user or any specified worker to simplify onboarding and HR processes.
  • Comprehensive job posting insights: Instantly retrieve information about job postings, including descriptions and screening questionnaires, to aid recruiters and hiring managers.
  • Interview feedback analysis: Let your agent pull and summarize interview feedback entries to streamline debriefs and improve hiring decisions.
  • Access to holiday and leave events: Quickly get holiday schedules and leave status values for better workforce planning and scheduling.

Supported Tools & Triggers

Tools
Triggers
Create Business Title ChangeCreates a business title change instance for a worker with the specified data.
Create Job ChangeTool to create a job change instance for a worker in Workday.
Create Payroll InputsTool to create payroll inputs in Workday.
Create Time Off RequestCreates a time off request for the specified worker and initiates the business process.
Get Absence BalanceRetrieves balance information for a specific worker's absence plan.
Get Assignment Change Group Cost CentersRetrieves cost center instances for organization assignment changes.
Get Assignment Change Group JobsRetrieves job instances for organization assignment changes.
Get Assignment TypesRetrieves assignment type values for job changes in Workday.
Get Business Title ChangeRetrieves a business title change instance by ID.
Get Business Title Change For WorkerTool to retrieve a business title change instance for a specific worker.
Get Candidate Availability TemplateTool to retrieve the candidate availability template version for a specific job posting.
Get Collection of JobsTool to retrieve a paginated collection of jobs from Workday Staffing system.
Get Collection of PayrollTool to retrieve a collection of payroll inputs from Workday.
Get Company Insider TypesRetrieves company insider types from Workday Staffing API.
Get Contingent Worker TypesTool to retrieve contingent worker types from Workday staffing API.
Get Country InfoRetrieves detailed information about a specific country from Workday.
Get CurrenciesRetrieves currency instances for job changes in Workday.
Get Current UserRetrieves the current authenticated worker's profile information from Workday.
Get GrantsRetrieves grant instances for organization assignment changes.
Get Headcount OptionsRetrieves headcount option instances that can be used as values for other endpoint parameters.
Get History Instance for WorkerTool to retrieve a specific history instance for a worker.
Get History Items for WorkerTool to retrieve a collection of history items for a specific worker.
Get Holiday EventsReturns the holiday events for the specified workers and time period.
Get InterviewTool to retrieve detailed information about a specific interview from Workday Recruiting.
Get Interview FeedbackRetrieves interview feedback for the specified interview ID from Workday Recruiting API.
Get Job By IDTool to retrieve detailed information about a single job instance by its ID.
Get Job Change FrequenciesRetrieves frequency instances for job changes in Workday.
Get Job Change Location InfoTool to retrieve location information for a specific job change in Workday.
Get Job Change PositionRetrieves position details for a specific job change in Workday Staffing API.
Get Job Change Reason InstanceRetrieves a job change reason instance from Workday.
Get Job Change ReasonsRetrieves a collection of job change reasons from Workday.
Get Job Change Reason ValuesRetrieves job change reason instances that can be used as values for other staffing endpoint parameters.
Get Job Changes Group TemplatesRetrieves job changes group template instances in Workday.
Get Job Changes Job ValuesRetrieves job instances that can be used as values for job changes parameters.
Get Job Changes Worker ValuesRetrieves worker instances that can be used as values for job changes parameters.
Get Job ClassificationsRetrieves job classification instances for job changes in Workday.
Get Job PostingRetrieves detailed information about a specific job posting including job description.
Get Job Posting QuestionnaireRetrieves screening questions and questionnaires associated with a specific job posting.
Get Job Profiles ValuesRetrieves job profile instances from Workday Staffing API.
Get Job Requisition ValuesRetrieves job requisition instances that can be used as values for other endpoint parameters.
Get Job WorkspaceTool to retrieve a single workspace instance for a specific job.
Get Job WorkspacesTool to retrieve a collection of workspaces for a specified job ID.
Get Leave Status ValuesGet all available leave status values from Workday.
Get My Job PostingsRetrieves job postings assigned to the authenticated user (current recruiter).
Get Organization Assignment Business UnitsRetrieves business unit instances for organization assignment changes.
Get Organization Assignment CustomsRetrieves custom organization assignment instances.
Get Organization Assignment FundsRetrieves fund instances for organization assignment changes.
Get Organization Assignment RegionsRetrieves region instances for organization assignment changes.
Get Organization Assignment WorkersRetrieves worker instances for organization assignment changes.
Get Pay Group by Job IDRetrieves the pay group for a specified job ID.
Get Payroll Input InstanceRetrieves detailed information for a single payroll input instance by ID.
Get Pay Slip Instance for WorkerRetrieves a specific pay slip instance for a worker.
Get Pay Slips for WorkerRetrieves a collection of pay slips for a specific worker.
Get Proposed Position ValuesRetrieves proposed position instances that can be used as values for job changes parameters.
Get ProspectRetrieves a single prospect instance for talent matching and best-fit analysis.
Get Prospect EducationsRetrieves the educational background of a prospect from Workday Recruiting API for talent matching and best-fit analysis.
Get Prospect ExperiencesRetrieves the work experience of a prospect for talent matching and best-fit analysis.
Get Prospect Resume AttachmentsRetrieves resume attachments for a specific prospect to help prepare for upcoming interviews.
Get Prospect SkillsRetrieves the skills of a prospect from Workday Recruiting API for talent matching and best-fit analysis.
Get Supervisory Organization ValuesRetrieves supervisory organization instances that can be used as values for job changes parameters.
Get Time Off Entries for WorkerRetrieves a collection of time off entries for a specific worker.
Get Time Off Plans For WorkerRetrieves a collection of time off plans for a specific worker.
Get Time Off Status ValuesRetrieves available time off status values from Workday.
Get Time TypesRetrieves time type values for job changes in Workday.
Get Worker Business Title ChangesRetrieves business title changes for a specific worker.
Get Worker Eligible Absence TypesRetrieves a collection of eligible absence types for the specified worker.
Get Worker InfoRetrieves detailed worker information including staffing data.
Get Worker Leaves of AbsenceRetrieves the Leaves Of Absence for the specified worker using the working absenceManagement v1 API.
Get Workers Collection StaffingTool to retrieve workers and current staffing information from Workday.
Get Worker Service DatesTool to retrieve service dates for a specified worker from Workday Staffing API v6.
Get Worker Staffing InformationTool to retrieve a worker's current staffing information from Workday.
Get Worker Time Off DetailsRetrieves a collection of time off details for the specified worker.
Get Worker TypesRetrieves worker type instances that can be used as values for job changes parameters.
Get Worker Valid Time Off DatesRetrieves valid time off dates for a worker, indicating when they are eligible to take time off.
Get Workspace InstancesTool to retrieve workspace instances that can be used as prompt values for other Workday API parameters.
Get Work Study AwardsRetrieves work study award instances for job changes in Workday.
List CountriesRetrieves country values from Workday Recruiting API.
List InterviewsRetrieves a list of interviews with job requisition and recruiter assignment details.
List Job PostingsRetrieves a paginated list of job postings from Workday Recruiting system.
List JobsRetrieves a collection of jobs from Workday Staffing system.
Retrieve Worker Leave of AbsenceRetrieves the leave of absence details for a specified worker.
Update An Existing PayrollTool to partially update an existing payroll input instance in Workday.
Update Job Change Business TitlePartially updates the business title for a specific job change.
Update Message Template By IDTool to update a message template in Workday by its ID.

What is the Composio tool router, and how does it fit here?

What is Composio SDK?

Composio's Composio SDK helps agents find the right tools for a task at runtime. You can plug in multiple toolkits (like Gmail, HubSpot, and GitHub), and the agent will identify the relevant app and action to complete multi-step workflows. This can reduce token usage and improve the reliability of tool calls. Read more here: Getting started with Composio SDK

The tool router generates a secure MCP URL that your agents can access to perform actions.

How the Composio SDK works

The Composio SDK follows a three-phase workflow:

  1. Discovery: Searches for tools matching your task and returns relevant toolkits with their details.
  2. Authentication: Checks for active connections. If missing, creates an auth config and returns a connection URL via Auth Link.
  3. Execution: Executes the action using the authenticated connection.

Step-by-step Guide

Prerequisites

Before starting, make sure you have:
  • Node.js 18 or higher
  • A Composio account with an active API key
  • An OpenAI API key
  • Basic familiarity with TypeScript

Getting API Keys for OpenAI and Composio

OpenAI API Key
  • Go to the OpenAI dashboard and create an API key.
  • You need credits or a connected billing setup to use the models.
  • Store the key somewhere safe.
Composio API Key
  • Log in to the Composio dashboard.
  • Go to Settings and copy your API key.
  • This key lets your Mastra agent talk to Composio and reach Workday through MCP.

Install dependencies

bash
npm install @composio/core @mastra/core @mastra/mcp @ai-sdk/openai dotenv

Install the required packages.

What's happening:

  • @composio/core is the Composio SDK for creating MCP sessions
  • @mastra/core provides the Agent class
  • @mastra/mcp is Mastra's MCP client
  • @ai-sdk/openai is the model wrapper for OpenAI
  • dotenv loads environment variables from .env

Set up environment variables

bash
COMPOSIO_API_KEY=your_composio_api_key_here
COMPOSIO_USER_ID=your_user_id_here
OPENAI_API_KEY=your_openai_api_key_here

Create a .env file in your project root.

What's happening:

  • COMPOSIO_API_KEY authenticates your requests to Composio
  • COMPOSIO_USER_ID tells Composio which user this session belongs to
  • OPENAI_API_KEY lets the Mastra agent call OpenAI models

Import libraries and validate environment

typescript
import "dotenv/config";
import { openai } from "@ai-sdk/openai";
import { Agent } from "@mastra/core/agent";
import { MCPClient } from "@mastra/mcp";
import { Composio } from "@composio/core";
import * as readline from "readline";

import type { AiMessageType } from "@mastra/core/agent";

const openaiAPIKey = process.env.OPENAI_API_KEY;
const composioAPIKey = process.env.COMPOSIO_API_KEY;
const composioUserID = process.env.COMPOSIO_USER_ID;

if (!openaiAPIKey) throw new Error("OPENAI_API_KEY is not set");
if (!composioAPIKey) throw new Error("COMPOSIO_API_KEY is not set");
if (!composioUserID) throw new Error("COMPOSIO_USER_ID is not set");

const composio = new Composio({
  apiKey: composioAPIKey as string,
});
What's happening:
  • dotenv/config auto loads your .env so process.env.* is available
  • openai gives you a Mastra compatible model wrapper
  • Agent is the Mastra agent that will call tools and produce answers
  • MCPClient connects Mastra to your Composio MCP server
  • Composio is used to create a Tool Router session

Create a Tool Router session for Workday

typescript
async function main() {
  const session = await composio.create(
    composioUserID as string,
    {
      toolkits: ["workday"],
    },
  );

  const composioMCPUrl = session.mcp.url;
  console.log("Workday MCP URL:", composioMCPUrl);
What's happening:
  • create spins up a short-lived MCP HTTP endpoint for this user
  • The toolkits array contains "workday" for Workday access
  • session.mcp.url is the MCP URL that Mastra's MCPClient will connect to

Configure Mastra MCP client and fetch tools

typescript
const mcpClient = new MCPClient({
    id: composioUserID as string,
    servers: {
      nasdaq: {
        url: new URL(composioMCPUrl),
        requestInit: {
          headers: session.mcp.headers,
        },
      },
    },
    timeout: 30_000,
  });

console.log("Fetching MCP tools from Composio...");
const composioTools = await mcpClient.getTools();
console.log("Number of tools:", Object.keys(composioTools).length);
What's happening:
  • MCPClient takes an id for this client and a list of MCP servers
  • The headers property includes the x-api-key for authentication
  • getTools fetches the tool definitions exposed by the Workday toolkit

Create the Mastra agent

typescript
const agent = new Agent({
    name: "workday-mastra-agent",
    instructions: "You are an AI agent with Workday tools via Composio.",
    model: "openai/gpt-5",
  });
What's happening:
  • Agent is the core Mastra agent
  • name is just an identifier for logging and debugging
  • instructions guide the agent to use tools instead of only answering in natural language
  • model uses openai("gpt-5") to configure the underlying LLM

Set up interactive chat interface

typescript
let messages: AiMessageType[] = [];

console.log("Chat started! Type 'exit' or 'quit' to end.\n");

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  prompt: "> ",
});

rl.prompt();

rl.on("line", async (userInput: string) => {
  const trimmedInput = userInput.trim();

  if (["exit", "quit", "bye"].includes(trimmedInput.toLowerCase())) {
    console.log("\nGoodbye!");
    rl.close();
    process.exit(0);
  }

  if (!trimmedInput) {
    rl.prompt();
    return;
  }

  messages.push({
    id: crypto.randomUUID(),
    role: "user",
    content: trimmedInput,
  });

  console.log("\nAgent is thinking...\n");

  try {
    const response = await agent.generate(messages, {
      toolsets: {
        workday: composioTools,
      },
      maxSteps: 8,
    });

    const { text } = response;

    if (text && text.trim().length > 0) {
      console.log(`Agent: ${text}\n`);
        messages.push({
          id: crypto.randomUUID(),
          role: "assistant",
          content: text,
        });
      }
    } catch (error) {
      console.error("\nError:", error);
    }

    rl.prompt();
  });

  rl.on("close", async () => {
    console.log("\nSession ended.");
    await mcpClient.disconnect();
    process.exit(0);
  });
}

main().catch((err) => {
  console.error("Fatal error:", err);
  process.exit(1);
});
What's happening:
  • messages keeps the full conversation history in Mastra's expected format
  • agent.generate runs the agent with conversation history and Workday toolsets
  • maxSteps limits how many tool calls the agent can take in a single run
  • onStepFinish is a hook that prints intermediate steps for debugging

Complete Code

Here's the complete code to get you started with Workday and Mastra AI:

typescript
import "dotenv/config";
import { openai } from "@ai-sdk/openai";
import { Agent } from "@mastra/core/agent";
import { MCPClient } from "@mastra/mcp";
import { Composio } from "@composio/core";
import * as readline from "readline";

import type { AiMessageType } from "@mastra/core/agent";

const openaiAPIKey = process.env.OPENAI_API_KEY;
const composioAPIKey = process.env.COMPOSIO_API_KEY;
const composioUserID = process.env.COMPOSIO_USER_ID;

if (!openaiAPIKey) throw new Error("OPENAI_API_KEY is not set");
if (!composioAPIKey) throw new Error("COMPOSIO_API_KEY is not set");
if (!composioUserID) throw new Error("COMPOSIO_USER_ID is not set");

const composio = new Composio({ apiKey: composioAPIKey as string });

async function main() {
  const session = await composio.create(composioUserID as string, {
    toolkits: ["workday"],
  });

  const composioMCPUrl = session.mcp.url;

  const mcpClient = new MCPClient({
    id: composioUserID as string,
    servers: {
      workday: {
        url: new URL(composioMCPUrl),
        requestInit: {
          headers: session.mcp.headers,
        },
      },
    },
    timeout: 30_000,
  });

  const composioTools = await mcpClient.getTools();

  const agent = new Agent({
    name: "workday-mastra-agent",
    instructions: "You are an AI agent with Workday tools via Composio.",
    model: "openai/gpt-5",
  });

  let messages: AiMessageType[] = [];

  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
    prompt: "> ",
  });

  rl.prompt();

  rl.on("line", async (input: string) => {
    const trimmed = input.trim();
    if (["exit", "quit"].includes(trimmed.toLowerCase())) {
      rl.close();
      return;
    }

    messages.push({ id: crypto.randomUUID(), role: "user", content: trimmed });

    const { text } = await agent.generate(messages, {
      toolsets: { workday: composioTools },
      maxSteps: 8,
    });

    if (text) {
      console.log(`Agent: ${text}\n`);
      messages.push({ id: crypto.randomUUID(), role: "assistant", content: text });
    }

    rl.prompt();
  });

  rl.on("close", async () => {
    await mcpClient.disconnect();
    process.exit(0);
  });
}

main();

Conclusion

You've built a Mastra AI agent that can interact with Workday through Composio's Tool Router. You can extend this further by:
  • Adding other toolkits like Gmail, Slack, or GitHub
  • Building a web-based chat interface around this agent
  • Using multiple MCP endpoints to enable cross-app workflows

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FAQ

What are the differences in Tool Router MCP and Workday MCP?

With a standalone Workday MCP server, the agents and LLMs can only access a fixed set of Workday tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Workday and many other apps based on the task at hand, all through a single MCP endpoint.

Can I use Tool Router MCP with Mastra AI?

Yes, you can. Mastra AI fully supports MCP integration. You get structured tool calling, message history handling, and model orchestration while Tool Router takes care of discovering and serving the right Workday tools.

Can I manage the permissions and scopes for Workday while using Tool Router?

Yes, absolutely. You can configure which Workday scopes and actions are allowed when connecting your account to Composio. You can also bring your own OAuth credentials or API configuration so you keep full control over what the agent can do.

How safe is my data with Composio Tool Router?

All sensitive data such as tokens, keys, and configuration is fully encrypted at rest and in transit. Composio is SOC 2 Type 2 compliant and follows strict security practices so your Workday data and credentials are handled as safely as possible.

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