Claude Code

Claude Code connects to MCP servers through a .mcp.json file in your project root or home directory. See the MCP server reference for the full tool list and response shapes.

Install the server

If you installed Plumb via cargo install plumb-cli, the plumb binary is already on your PATH. If you built from source, make sure the binary is accessible from the directory where Claude Code runs.

Configure .mcp.json

Create or edit .mcp.json in your project root:

{
  "mcpServers": {
    "plumb": {
      "command": "plumb",
      "args": ["mcp"]
    }
  }
}

For a source checkout (useful when hacking on Plumb itself):

{
  "mcpServers": {
    "plumb": {
      "command": "cargo",
      "args": ["run", "--quiet", "-p", "plumb-cli", "--", "mcp"]
    }
  }
}

Verify the connection

After saving .mcp.json, restart Claude Code or run /mcp in the Claude Code prompt to list connected servers. You should see plumb with its tools (lint_url, explain_rule, list_rules, get_config, echo).

Run a quick smoke test by asking Claude Code:

Use plumb’s echo tool to send “hello”.

If the tool returns your message, the transport is working.

Lint a page

Ask Claude Code:

Use plumb to lint https://example.com

Claude Code calls lint_url and returns a compact summary of violations. Use detail: "full" when you need the complete JSON envelope (capped at 50 KB).

Common issues

PATH resolution, working directory, large responses, and tool approval prompts apply to every agent integration. See Common issues for the consolidated list.

The Claude-specific note: when plumb is not on the GUI-process PATH, point .mcp.json at the absolute binary path (e.g. /Users/you/.cargo/bin/plumb) rather than the bare plumb command.

See also

• MCP server reference — tool list, response shapes, resource URIs.
• Configuration — plumb.toml reference.
• Install — binary installation options.