Connecting clients

All snippets assume the instance at https://rustpad.example.net.

Claude Code

claude mcp add rustpad --env RUSTPAD_URL=https://rustpad.example.net -- npx -y rustpad-mcp

Claude Desktop

claude_desktop_config.json:

{
  "mcpServers": {
    "rustpad": {
      "command": "npx",
      "args": ["-y", "rustpad-mcp"],
      "env": {
        "RUSTPAD_URL": "https://rustpad.example.net"
      }
    }
  }
}

Codex

~/.codex/config.toml:

[mcp_servers.rustpad]
command = "npx"
args = ["-y", "rustpad-mcp"]

[mcp_servers.rustpad.env]
RUSTPAD_URL = "https://rustpad.example.net"

Docker

docker run -i --rm -e RUSTPAD_URL=https://rustpad.example.net ghcr.io/ni-c/rustpad-mcp

As an MCP client entry:

{
  "mcpServers": {
    "rustpad": {
      "command": "docker",
      "args": [
        "run", "-i", "--rm",
        "-e", "RUSTPAD_URL=https://rustpad.example.net",
        "ghcr.io/ni-c/rustpad-mcp"
      ]
    }
  }
}

A read-only connection

Append RUSTPAD_READ_ONLY=true to any of the above and only get_document, get_document_info and get_stats are registered — the write tools do not exist for that connection, rather than being refused at call time.

Through mcp-hub

mcp-hub serves many stdio MCP servers from one container behind a single HTTPS endpoint, so rustpad-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, with the hub's own filter alongside:

{
  "mcpServers": {
    "rustpad": {
      "command": "npx",
      "args": ["-y", "rustpad-mcp"],
      "env": { "RUSTPAD_ALLOW_TOOLS": "essential" },
      "denyTools": ["set_document"]
    }
  }
}

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 rustpad-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/rustpad/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.