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Arbor MCP

Arbor ships a dedicated arbor-mcp binary from the arbor-mcp crate. It exposes Arbor's daemon-backed state over stdio using the Model Context Protocol.

Requirements

arbor-mcp talks to arbor-httpd, so the daemon must be reachable first.

Relevant environment variables:

  • ARBOR_DAEMON_URL: daemon base URL. Default: http://127.0.0.1:8787
  • ARBOR_DAEMON_AUTH_TOKEN: bearer token for remote authenticated daemons

The stdio server is enabled by the crate's default stdio-server feature.

Enabling the Server

Build the MCP server with default features:

cargo build -p arbor-mcp

Run it directly against a daemon:

ARBOR_DAEMON_URL=http://127.0.0.1:8787 cargo run -p arbor-mcp

Local Development

Run Arbor's daemon and MCP server together:

just run-mcp

Client Example

{
  "mcpServers": {
    "arbor": {
      "command": "/path/to/arbor-mcp",
      "env": {
        "ARBOR_DAEMON_URL": "http://127.0.0.1:8787"
      }
    }
  }
}

Remote Access and Auth

arbor-mcp does not implement a second auth layer. It forwards requests to arbor-httpd, and the daemon enforces remote auth.

Daemon behavior:

  • Loopback clients (127.0.0.1, ::1, localhost) are allowed without a token
  • Non-loopback clients require a configured [daemon] auth_token
  • When [daemon] auth_token is configured, the daemon binds remotely by default on 0.0.0.0:8787
  • ARBOR_HTTPD_BIND can override the bind address in either mode

To enable remote MCP access:

  1. On the machine running arbor-httpd, set an auth token in ~/.config/arbor/config.toml:
[daemon]
auth_token = "replace-me"
  1. Start or restart arbor-httpd.
  2. In the MCP client environment, point arbor-mcp at the remote daemon and provide the same token:
{
  "mcpServers": {
    "arbor": {
      "command": "/path/to/arbor-mcp",
      "env": {
        "ARBOR_DAEMON_URL": "http://remote-host:8787",
        "ARBOR_DAEMON_AUTH_TOKEN": "replace-me"
      }
    }
  }
}

arbor-mcp sends the token as Authorization: Bearer <token>. If the token is missing or wrong, the daemon rejects the request.

Features

Arbor's MCP server exposes:

  • Tools for repositories, worktrees, changed files, git commit/push, terminals, processes, tasks, and agent activity
  • Resources for daemon snapshots such as arbor://health, arbor://processes, and arbor://tasks
  • Prompts for common Arbor workflows such as reviewing a worktree or stabilizing a process

Today the MCP surface focuses on daemon-backed worktree, terminal, process, and task flows. Issue browsing and managed-worktree previews still live in the GUI and web surfaces.

Disabling the Binary

The stdio server binary is cargo-feature gated:

cargo build -p arbor-mcp --no-default-features

To make the feature explicit, build it with:

cargo build -p arbor-mcp --features stdio-server