Plugin MCP Registration

How Auto-Prefixing Works

• **Registration** — Place a .mcp.json file alongside your plugin.json. The MCP servers defined there are automatically started when the plugin loads.
• **Auto-prefix format** — Plugin MCP tools get the prefix `mcp__plugin_<plugin-name>_<server-name>__<tool-name>`, preventing name collisions between plugins.
• **Why it matters** — Two plugins could both register a server named 'api'. Without prefixing they'd collide. With prefixing they coexist: `mcp__plugin_pluginA_api__call` vs `mcp__plugin_pluginB_api__call`.
• **Our plugin MCP servers**
  • › AEM (stdio) — JCR content queries and component inspection
  • › Chrome DevTools (stdio) — browser automation and screenshots
  • › Figma (HTTP) — design extraction and token mapping
  • › axe (Docker) — accessibility testing and compliance

Getting the Prefix Right

1. 1 **Always use the full prefix in skills and agents**
   • › Plugin server: `mcp__plugin_dx-aem_AEM__getNodeContent`
   • › Project-level server: `mcp__ado__getWorkItem`
   • › WRONG: `mcp__AEM__getNodeContent` (missing plugin prefix)
2. 2 **The common mistake** — Using the shorthand `mcp__AEM__getNodeContent` instead of the full `mcp__plugin_dx-aem_AEM__getNodeContent`. The shorthand doesn't match the actual registered tool names, causing 'tool not found' failures.
3. 3 **Copy, don't guess** — When writing skills that call MCP tools, copy the exact tool name from Claude Code's tool list. Never guess the prefix format.
4. 4 **Verify your setup** — Check .mcp.json in your installed plugins and match the server names to the prefixed tool names you see in Claude Code.