Connecting clients

Claude Code

claude mcp add caldav-mcp -- npx -y @ni-c/caldav-mcp

Claude Desktop

Codex

MCP Inspector

Docker

Through mcp-hub

mcp-hub serves many stdio MCP servers from one container behind a single HTTPS endpoint, so caldav-mcp can be reached from clients that cannot spawn a local process — ChatGPT connectors, Claude on the web, Cursor — without a container, a hostname and an OAuth stack of its own.

Its /config/mcp.json uses Claude Code's format, so the entry is the one you already have:

{
  "mcpServers": {
    "caldav-mcp": {
      "command": "npx",
      "args": ["-y", "@ni-c/caldav-mcp"],
      "env": {
        "CALDAV_URL": "https://service.example.com",
        "CALDAV_TOKEN": "…",
        "CALDAV_ALLOW_TOOLS": "essential"
      },
      "denyTools": ["delete_event"]
    }
  }
}

allowTools and denyTools are the hub's own per-server filter and take exact tool names or list_* prefixes — the same syntax as the two environment variables, so a list moves between them verbatim. What does not move is essential: that preset is a caldav-mcp feature and belongs in env as shown. "allowTools": ["essential"] would be a name the hub cannot resolve.

The two compose, and it is worth knowing which does what: the server registers what its environment variables allow, and the hub exposes what its arrays allow. Filtering in the server is the tighter of the two — the tool is never built.

Register https://your-host/caldav-mcp/mcp as a connector and you get this server alone. Register the hub's /hub endpoint instead and you reach every server behind it through six meta-tools, which is the answer worth having once you run several of these at once.