mattt/Companion

Companion is a utility for testing and debugging your MCP servers
on macOS, iOS, and visionOS.
It's built using the
official Swift SDK.
> [!IMPORTANT]
> Companion is in early development.
> It implements the MCP client feature set through protocol version 2025-11-25,
> with two exceptions.
> Sampling runs without tool use,
> so a server that asks for sampling with tools gets a text completion.
> The experimental Tasks feature is not supported by the Swift SDK yet.
> For another MCP debugging experience, check out the
> MCP Inspector.
## Features
[x] Connect to local (STDIO) and remote (Streamable HTTP) MCP servers
[x] Browse prompts, resources, and tools, with live list updates
[x] Call tools with progress reporting, cancellation, and structured output
[x] Generate prompts and read resources,
with argument completions and resource subscriptions
[x] View server log messages and set the logging level
[x] Ping servers to check that they respond
[x] Answer sampling requests with Apple Foundation Models
or your own OpenAI, Anthropic, Gemini, or Ollama model
[x] Respond to elicitation requests in form and URL modes
[x] Share per-server roots with servers that ask for them
[x] Authenticate with custom headers, a bearer token, or OAuth 2.1 sign-in
## Getting Started
First, download the Companion app
(requires macOS 15 or later).
Or, if you have Homebrew installed,
you can run the following command:
console
brew install --cask mattt/tap/Companion
When you open the app,
you'll see a sidebar on the left and a placeholder view on the right.
Click the + button in the toolbar to add an MCP server.
> [!TIP]
> Looking for a fun MCP server?
> Check out iMCP,
> which gives models access to your Messages, Contacts, Reminders and more.
> Click on the iMCP menubar icon,
> select "Copy server command to clipboard",
> and paste that into the "Command" field for your STDIO server.
Once you add a server,
it'll automatically connect.
When it does, it'll show available prompts, resources, and tools.
Click on one of those sections to see a list, and drill into whatever you're interested in.
Or, select the parent item in the sidebar to get information about the server.