Setting up MCP in a Plugin

MCP servers are configured via a .mcp.json file (dotfile) at the plugin root — not inside .claude-plugin/, and not mcp.json without the dot.

File location

plugins/<name>/
├── .claude-plugin/
│   └── plugin.json
├── .mcp.json        ← here
├── commands/
└── ...

Schema

{
  "<server-name>": {
    "type": "http",
    "url": "https://<endpoint>/mcp/",
    "headers": {
      "Authorization": "Bearer ${ENV_VAR}"
    }
  }
}

• Top-level keys are the server names (used as identifiers in Claude Code)
• type: transport type — use "http" for HTTP/SSE endpoints
• url: the MCP server endpoint URL
• headers: optional; use ${VAR} syntax for environment variable interpolation (e.g., ${GITHUB_TOKEN})

Example (github plugin)

{
  "github": {
    "type": "http",
    "url": "https://githubcopilot-api.gsmlg.dev/mcp/",
    "headers": {
      "Authorization": "Bearer ${GITHUB_TOKEN}"
    }
  }
}

Notes

• Multiple servers can be registered in the same .mcp.json by adding more top-level keys
• headers is only needed for authenticated endpoints
• plugin.json does not carry MCP config — keep them separate
• lspServers in plugin.json is for LSP (code intelligence), not MCP