What is copilot-cowork-plugin?

A packaging tool that turns an existing agent skill into a Microsoft 365 app package for Copilot Cowork. It creates the package details, handles unsupported file formats, and validates the result with a command-line tool.

Use it to package and check an existing SKILL.md folder for Copilot Cowork deployment.

It prepares a local skill for use in a Microsoft 365 tenant without creating or changing the skill itself.

copilot-cowork-plugin — Plugin for Claude Code by Yesterday-AI/skills

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Clone the repo

git clone --depth 1 https://github.com/Yesterday-AI/skills

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/plugins/yesterday-ai/skills/copilot-cowork-plugin/github.svg)](https://agentmods.dev/plugins/yesterday-ai/skills/copilot-cowork-plugin)

Your own site

<a href="https://agentmods.dev/plugins/yesterday-ai/skills/copilot-cowork-plugin"><img src="https://agentmods.dev/badge/plugins/yesterday-ai/skills/copilot-cowork-plugin/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/plugins/yesterday-ai/skills/copilot-cowork-plugin"><img src="https://agentmods.dev/badge/plugins/yesterday-ai/skills/copilot-cowork-plugin.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session not measured What this adds to a session before it is invoked.

When invoked not measured The manifest loads nothing itself; its 1 skill cost 82 tokens a session between them.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Security

Grade A, and why

copilot-cowork-plugin scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.compiled/skill-plugins/copilot-cowork-plugin/.claude-plugin/plugin.json · 15 lines

What it actually says

{
  "name": "copilot-cowork-plugin",
  "description": "Verpackt einen bestehenden Agent-Skill als Microsoft-365-App-Paket f\u00fcr Copilot Cowork \u2014 Manifest, Icons, Konvertierung abgelehnter Dateiformate und Vorab-Validierung per CLI. F\u00fcr den Weg vom lokalen SKILL.md-Ordner in den M365-Tenant; schreibt selbst keine Skills und betrifft nicht Anthropics Claude Cowork.",
  "author": {
    "name": "Yesterday"
  },
  "homepage": "https://github.com/Yesterday-AI/skills/tree/main/.compiled/skill-plugins/copilot-cowork-plugin",
  "repository": "https://github.com/Yesterday-AI/skills",
  "license": "MIT",
  "keywords": [
    "skills",
    "copilot-cowork-plugin"
  ]
}

Contents

What it installs

The manifest is a name and a version. 1 skill travel with it, and installing the plugin installs all of them — 82 tokens a session between them. Each is measured on its own page, and each can be installed alone.

Skill copilot-cowork-plugin A 82 tokens

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

1mo ago First seen · 15 lines scan A 6e9b8ffebbf1

Subscribe to this mod's changes

copilot-cowork-plugin is a plugin published in the GitHub repository Yesterday-AI/skills (2 stars, last pushed 1mo ago), licensed MIT. Its token cost is not measured: this kind of file is read by the harness, not the model. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-10-14.

Building agents agent-skills ai-agents claude-code-plugins cursor cursor-plugins

copilot-cowork-plugin next to 6 plugins from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
copilot-cowork-pluginYesterday-AI/skills	Plugin	2	1mo ago	MIT	A	—	Claude Code
before-you-buildwshobson/agents	Plugin	42k	4d ago	MIT	A	—	Claude Code
handbook-agent-spec-kitNikiforovAll/claude-code-rules	Plugin	142	11d ago	Apache-2.0	A	—	Claude Code
mc-agent-toolkitmonte-carlo-data/mc-agent-toolkit	Plugin	93	yesterday	Apache-2.0	A	—	Cursor
pedantic-coderoborchers/fractional-cto	Plugin	37	19d ago	MIT	A	—	Claude Code
python-packageoborchers/fractional-cto	Plugin	37	19d ago	MIT	A	—	Claude Code
mosaic-bridgeMosaicXR-AI/mosaic-bridge	Plugin	11	today	none	A	—	Claude Code