Introduce "Agent Skills Plugins" for Claude and Github CLI

.claude-plugin/marketplace.json

@@ -0,0 +1,15 @@
+{
+  "name": "microsoft-agents-sdk",
+  "owner": { "name": "Microsoft" },
+  "metadata": {
+    "description": "Claude Code skills for building agents with the Microsoft Agents SDK"
+  },
+  "plugins": [
+    {
+      "name": "agents-for-js",
+      "source": "./agent-plugins/agents-for-js",
+      "description": "Skills for building agents with the Microsoft 365 Agents SDK for TypeScript/JavaScript",
+      "version": "1.0.0"
+    }
+  ]
+}

agent-plugins/CONTRIBUTING.md

@@ -0,0 +1,105 @@
+# Contributing to Agent Plugins
+
+This guide explains how to add new skills, update existing skills, and add new plugins to this marketplace.
+
+---
+
+## How It's Organized
+
+```
+.claude-plugin/marketplace.json          ← top-level marketplace registry
+agent-plugins/
+  agents-for-js/                         ← a plugin
+    plugin.json                          ← plugin metadata
+    skills/
+      <skill-name>/
+        SKILL.md                         ← the skill content
+```
+
+The **marketplace registry** (`/.claude-plugin/marketplace.json`) lists the plugins available for install. Each **plugin** groups related skills for a language or platform. Each **skill** is a Markdown file with a YAML frontmatter block that tells the AI assistant when to activate it.
+
+---
+
+## Adding a New Skill to an Existing Plugin
+
+1. **Create a directory** under the plugin's `skills/` folder. Name it after the skill using lowercase and hyphens:
+
+   ```
+   agent-plugins/agents-for-js/skills/my-new-skill/
+   ```
+
+2. **Create `SKILL.md`** in that directory with a YAML frontmatter block:
+
+   ```markdown
+   ---
+   name: my-new-skill
+   description: Use when [trigger condition that activates this skill]
+   ---
+
+   # Skill Title
+
+   Skill content here...
+   ```
+
+3. **Write a precise `description`** — this is the trigger condition the AI uses to decide when to load the skill. Be specific:
+   - Good: `Use when any code imports @microsoft/agents-hosting or when building a new agent`
+   - Too vague: `Use for agents`
+   - Too broad: `Use when working with JavaScript`
+
+4. **No registration needed** — skills are auto-discovered from the `skills/` directory via the `"skills": "skills/"` entry in `plugin.json`.
+
+---
+
+## Updating an Existing Skill
+
+Edit the `SKILL.md` file directly. There is no build step — changes take effect the next time the plugin is loaded.
+[Updating the version](#versioning) will cause most agentic clients to update the skill automatically.
+
+---
+
+## Adding a New Plugin
+
+A plugin groups skills for a new language, platform, or use case (e.g., a `agents-for-dotnet` plugin).
+
+1. **Create a plugin directory** under `agent-plugins/`:
+
+   ```
+   agent-plugins/agents-for-dotnet/
+   ```
+
+2. **Add `plugin.json`**:
+
+   ```json
+   {
+     "name": "agents-for-dotnet",
+     "description": "Skills for building agents with the Microsoft 365 Agents SDK for .NET",
+     "version": "1.0.0",
+     "author": {
+       "name": "Microsoft"
+     },
+     "license": "MIT",
+     "keywords": ["microsoft", "agents", "teams", "dotnet"],
+     "skills": "skills/"
+   }
+   ```
+
+3. **Add skills** following the steps in [Adding a New Skill](#adding-a-new-skill-to-an-existing-plugin).
+
+4. **Register the plugin** in `/.claude-plugin/marketplace.json` by adding an entry to the `plugins` array:
+
+   ```json
+   {
+     "name": "agents-for-dotnet",
+     "source": "./agent-plugins/agents-for-dotnet",
+     "description": "Skills for building agents with the Microsoft 365 Agents SDK for .NET",
+     "version": "1.0.0"
+   }
+   ```
+
+5. **Document it** in `agent-plugins/README.md` — add the plugin to the Available Plugins table and list its skills.
+
+---
+
+## Versioning
+
+Bump the `version` field in `plugin.json` when making significant changes to a plugin's skills. This helps users know when to reinstall.

agent-plugins/README.md

@@ -0,0 +1,69 @@
+# Agent Plugins
+
+This directory contains AI coding assistant plugins for the Microsoft Agents SDK.
+
+Plugins provide skills — contextual guidance that activates automatically when you work on relevant code. When you import `@microsoft/agents-hosting`, your assistant gets Agents SDK knowledge loaded into context.
+
+## Available Plugins
+
+### `agents-for-js`
+
+Skills for building agents with the Microsoft 365 Agents SDK for TypeScript/JavaScript.
+
+| Skill | Activates when... |
+|-------|-------------------|
+| `agents-sdk-typescript` | Code imports `@microsoft/agents-hosting`, `@microsoft/agents-hosting-express`, or related packages, or when building a new agent |
+| `agents-sdk-debugging` | Resolving problems with a Microsoft Agents SDK agent |
+| `azure-agents-sdk-provision` | Provisioning Azure Bot resources, configuring identity credentials, or setting up OAuth via `az` CLI |
+
+---
+
+## Installing the Plugin Marketplace
+
+The plugin marketplace is hosted at the root of this repository (`.claude-plugin/marketplace.json`).
+
+### Claude Code
+
+Run these commands inside Claude Code:
+
+```
+/plugin marketplace add microsoft/Agents
+```
+
+Then install the plugin:
+
+```
+/plugin install agents-for-js@microsoft-agents-sdk
+```
+
+Skills activate automatically based on what you're working on — no manual loading needed.
+
+To verify installation:
+
+```
+/plugin
+```
+
+### GitHub Copilot CLI
+
+Add the marketplace:
+
+```
+/plugin marketplace add microsoft/Agents
+```
+
+Then install the plugin:
+
+```
+/plugin install agents-for-js@microsoft-agents-sdk
+```
+
+---
+
+## How Skills Work
+
+Skills are Markdown files with a YAML frontmatter block that defines a `name` and `description`. The `description` is used by the AI assistant to decide when to activate the skill — it acts as a trigger condition.
+
+When a skill activates, its full content is loaded into the assistant's context, giving it precise knowledge of the SDK's APIs, patterns, and common mistakes.
+
+To browse skill content directly, see the [`agents-for-js/skills/`](./agents-for-js/skills/) directory.

agent-plugins/agents-for-js/.claude-plugin/plugin.json

@@ -0,0 +1,4 @@
+{
+  "name": "agents-for-js",
+  "description": "Skills for building agents with the Microsoft 365 Agents SDK for TypeScript/JavaScript"
+}

agent-plugins/agents-for-js/plugin.json

@@ -0,0 +1,11 @@
+{
+  "name": "agents-for-js",
+  "description": "Skills for building agents with the Microsoft 365 Agents SDK for TypeScript/JavaScript",
+  "version": "1.0.0",
+  "author": {
+    "name": "Microsoft"
+  },
+  "license": "MIT",
+  "keywords": ["microsoft", "agents", "teams", "copilot-studio", "m365"],
+  "skills": "skills/"
+}