Rajeev Pentyala – Technical Blog on Power Platform, Azure and AI

Microsoft 365 Copilot Cowork can be extended with plugins. A plugin is a ZIP file that carries one or more skills, and an optional connector to a remote MCP server.

This is a beginner level post. Lets build a small plugin from an empty folder, package it, upload it to Cowork, and test it with a sample file.

What This Does

The example plugin reviews Power Platform solutions.

• Two skills. One audits an exported solution, the other designs a Dataverse schema.
• One connector to the Microsoft Learn MCP server, so findings cite official documentation.
• No server to host. The Learn MCP server is public and needs no authentication.
• Everything is plain Markdown and JSON. There is no code to compile.

Prerequisites

Make sure you have the following ready.

• A Microsoft 365 Copilot license with Cowork available.
• A text editor. Visual Studio Code works well.
• Two PNG icons. A 192×192 color icon and a 32×32 outline icon.

Lets start by creating the folder structure.

Create the Plugin Folder

• A plugin is just a folder with a fixed shape. Create the following.

powerplatform-solution-reviewer/
├── manifest.json
├── color.png
├── outline.png
├── tools/
│   └── learn-mcp-tools.json
└── skills/
    ├── solution-health-check/
    │   ├── SKILL.md
    │   └── references/
    │       ├── alm-checklist.md
    │       └── scoring-rubric.md
    └── dataverse-schema-review/
        ├── SKILL.md
        └── references/
            └── naming-conventions.md

Write a Skill

• Each skill is a folder containing a SKILL.md file.
• The file has YAML frontmatter at the top and Markdown instructions below it.

---
name: solution-health-check
description: |
  Audits an EXISTING, already-built Power Platform solution for ALM readiness and deployment risk.
  Use when the user attaches or pastes a solution.xml or customizations.xml file, a solution
  component list, or a solution export, and asks to "review my solution", "check my solution before
  deployment", or "is this solution ready for production".
  Do NOT use when the user is designing a new data model or asking what tables and columns to create
  before anything is built - use dataverse-schema-review for that instead.
license: MIT
metadata:
  author: Rajeev Pentyala
  version: "1.0"
---
# Power Platform Solution Health Check
## Workflow
1. Identify the solution: unique name, version, publisher, prefix, and managed or unmanaged.
2. Inventory components by type.
3. Check each item in `references/alm-checklist.md`.
4. Score using `references/scoring-rubric.md`.

• Two frontmatter fields are required.

Important: The folder name must match the name field. A mismatch is the most common reason a skill never loads.

The description is important. Cowork reads it to decide which skill to run. When you have two skills, add a “Do NOT use when” line that points at the sibling skill. Without it, the wrong skill can pick up the request.

Content loads in three layers, so the context window stays small.

• Frontmatter loads always, at startup.
• The SKILL.md body loads when the skill triggers. Aim for 1,500 to 2,000 words.
• Files under references/ load only when the skill asks for them.

That is why detailed checklists belong in references/ and not in SKILL.md.

Now we have the skills written. Lets add the connector.

Add a Connector

• A connector points Cowork at a remote MCP server. This example uses the Microsoft Learn MCP server, which is public.
• Every connector needs a tool description file that you package inside the ZIP. Create tools/learn-mcp-tools.json.

{
  "tools": [
    {
      "name": "microsoft_docs_search",
      "description": "Search official Microsoft Learn documentation and return relevant content excerpts with article titles and URLs.",
      "inputSchema": {
        "type": "object",
        "properties": {
          "query": {
            "type": "string",
            "description": "A query or topic about Microsoft products, services, platforms, or APIs."
          }
        },
        "required": ["query"]
      },
      "annotations": {
        "title": "Microsoft Docs Search",
        "readOnlyHint": true
      }
    }
  ]
}

Note: Authorization type None works here because the Learn MCP server is public. For your own API, use OAuthPluginVault and register an OAuth client first.

Create the Manifest

• The manifest is the ID card of the plugin.
• Create manifest.json file in the plugin root.

{
  "$schema": "https://developer.microsoft.com/json-schemas/teams/v1.28/MicrosoftTeams.schema.json",
  "manifestVersion": "1.28",
  "version": "1.0.0",
  "id": "YOUR-GUID-HERE",
  "developer": {
    "name": "Rajeev Pentyala",
    "websiteUrl": "https://rajeevpentyala.com",
    "privacyUrl": "https://rajeevpentyala.com/privacy",
    "termsOfUseUrl": "https://rajeevpentyala.com/terms"
  },
  "name": {
    "short": "Solution Reviewer",
    "full": "Power Platform Solution Reviewer for Copilot Cowork"
  },
  "description": {
    "short": "Reviews Power Platform solutions for ALM readiness and Dataverse schema quality",
    "full": "Audits an exported Power Platform solution for ALM readiness, and reviews proposed Dataverse data models against naming and relationship conventions."
  },
  "icons": {
    "color": "color.png",
    "outline": "outline.png"
  },
  "accentColor": "#742774",
  "agentSkills": [
    { "folder": "./skills/solution-health-check" },
    { "folder": "./skills/dataverse-schema-review" }
  ],
  "agentConnectors": [
    {
      "id": "microsoft-learn-mcp",
      "displayName": "Microsoft Learn MCP Server",
      "description": "Grounds every review finding in official Microsoft Learn documentation.",
      "toolSource": {
        "remoteMcpServer": {
          "mcpServerUrl": "https://learn.microsoft.com/api/mcp",
          "mcpToolDescription": {
            "file": "tools/learn-mcp-tools.json"
          },
          "authorization": {
            "type": "None"
          }
        }
      }
    }
  ]
}

• Here is what each field is for, and the value used above.

• Generate a GUID. You can this tool to generate new GUID. Then paste the result into id field of the manifest file.

Package as a ZIP

Cowork expects the plugin contents at the root of the ZIP. There must be no wrapper folder around them.

• Open the powerplatform-solution-reviewer folder.
• Select all five items inside it. Those are manifest.json, color.png, outline.png, the tools folder, and the skills folder.
• Right click the selection and choose Send to, then Compressed (zipped) folder.
• Windows names the ZIP after the item you right clicked. Rename it to powerplatform-solution-reviewer.zip.

Note: Select the five items inside the folder, not the folder itself. Right clicking the folder puts everything one level deep inside the ZIP, and the upload fails.

The package is ready. Lets upload it to Cowork.

Deploy the Plugin

• Open Copilot and switch to the Cowork tab.
• Select Customize in the left navigation.
• On the Plugins tab select Add plugin at the top right.
• Drag the ZIP onto the dialog, or select choose a file.

• Upload the Plugin .zip file prepared in the above section.
• The Share dialog opens next. Pick Only you while testing, then select Apply.

• The plugin now appears under Installed with its toggle on.

• Select the plugin row to open its detail page. Confirm both skills and the MCP server are listed.

Tip: If a skill is missing from this page, the problem is in the manifest or in the folder name. Check the folder to name match first.

The plugin is installed. Now lets test it.

Test the Plugin

• In the Cowork, select New task.
• Attach an exported solution ZIP and type a prompt that matches the skill description.

• Cowork reads the files inside the solution ZIP
  • Watch the response header. It names the skill that fired.
  • The Workspace panel on the right lists the plugin under Skills & Plugins.
  • The Microsoft docs search entries confirm the MCP connector is working.

• The final report shows the score, the arithmetic behind it, and findings with links to Microsoft Learn.

That is a plugin built, deployed, and tested. Here is a quick recap.

Summary

We created a plugin folder, wrote two skills, added a public MCP connector, packaged it, and tested it in Cowork.

• A plugin is a ZIP with manifest.json, two icons, a skills/ folder, and an optional tools/ folder.
• The skill folder name must match the name in the SKILL.md frontmatter.
• The description field decides when a skill runs, so write it with real user phrases.
• Keep long checklists in references/, because they load only when needed.
• Every MCP connector needs a tool description file packaged inside the ZIP.
• Upload from Cowork then Customize then Plugins then Add plugin.

Official documentation: Build plugins for Copilot Cowork and Customize Copilot Cowork

🙂