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Agent Workbench by Celest

Make it yours.

Open a Microsoft 365 Copilot agent package, see what it contains, refine the instructions that matter, and review your changes before exporting the next version.

Sign up Read the Microsoft 365 preview guide

Account and Microsoft 365 setup stay separate. Start your way: create a Celest account for account and setup tools, or read the Microsoft 365 preview guide for host-specific context.

Make It Yours01:04 Watch on YouTube (opens in a new tab)

Agent Workbench access

Start where you are.

Account and Microsoft 365 setup stay separate. Start with account and setup tools, or use the preview guide for the service where you work.

Celest account

Sign up

Create your Celest account and manage setup from one place. This does not install anything in Microsoft 365.

Open account setup
Microsoft 365

Add to Microsoft 365

Install the Agent Workbench package from Microsoft Marketplace. This route is independent from creating a Celest account.

Listing destination pending review — no Marketplace URL is linked yet.

Already have a package? Read the Microsoft 365 preview guide for host-specific context.

01 Open the package02 Refine an instruction03 Review the change04 Export the next version

A focused package loop

Give your agent a clearer job.

Agent Workbench combines tools for building, evaluating, and repairing Microsoft 365 Copilot agents. This workflow starts with an app package: its agent definition, instructions, icons, and supporting files.

  1. 01 OPEN

    Start with the package you have.

    See your agent’s instructions, settings, and files together in Agent Canvas.

  2. 02 REFINE

    Make one focused edit.

    Change an instruction in place, then compare the source text with its readable preview.

  3. 03 REVIEW

    Check the working copy.

    Run the package check and read what it flags before you export.

  4. 04 EXPORT

    Download the next version.

    Export the updated package. Your original stays available.

Inside the workbench

Real package work, made easy to see.

Explore the Weekly Brief agent’s package, instruction editor, and review and export controls.

Agent Workbench package overview, focused on the Weekly Brief agent’s instructions Opens the full screenshot in a new tab.
OpenSee the agent’s instructions and package details.View full screenshot of the package overview (opens in a new tab)
Instruction editor with a highlighted source change and readable preview. Opens the full screenshot in a new tab.
RefineEdit one instruction and check the rendered preview.

“Make accountability explicit: when a note names an owner or target date, keep both attached to the action. If either is missing, say so.” The adjacent preview renders that rule in readable Markdown.

View full screenshot of the instruction editor (opens in a new tab)
Review and export panel with a readable package check and latest Doctor run. Opens the full screenshot in a new tab.
Review & exportRun the local check, then export the corrected package.

The read-only check completed locally with 0 findings and 0 environment-dependent checks deferred, without changing files. The latest local Doctor run is ready for Microsoft validation: revision 3 · 0 repaired · 0 remaining · corrected package available.

View full screenshot of the review and export panel (opens in a new tab)

Actual Agent Workbench screens · Weekly Brief is a fictional example

Where the work lives

Work in the tools you already use.

Use Agent Workbench with Microsoft 365 Copilot or Copilot Cowork. The Microsoft 365 preview guide explains host-specific context and invited access.

In the Copilot conversation

Microsoft 365 Copilot

Inspect and improve your agent alongside the Copilot conversation.

Read the Copilot guide
In a Cowork task

Copilot Cowork

Attach a package ZIP to a Copilot Cowork task to inspect, revise, and repair its files.

Read the Cowork guide
Your changesEasy to review

Review your changes before using the next version.

Your originalKept available

Work on the next version with the original package close by.

Your next testIn Microsoft 365

Package checks help you prepare. Test the updated agent in the Microsoft service where you will use it.

Your next move

Got an agent in mind?

Start your way: create a Celest account for account and setup tools, or read the Microsoft 365 preview guide for host-specific context and invited access.

Sign upRead the Microsoft 365 preview guide