Companion is a free utility designed for testing and debugging MCP servers across macOS, iOS, and visionOS platforms. Built with the official Swift SDK, it enables users to connect to both local and remote servers, browse available prompts, resources, and tools, and efficiently call tools while generating prompts with specific arguments. The interface features a sidebar for easy navigation, allowing users to add servers and access various functionalities with just a few clicks.

Currently in early development, Companion is missing some key features such as authentication and sampling. Despite this, it provides a streamlined experience for users looking to interact with MCP servers. Requirements for installation include macOS Sequoia 15 or later, Xcode 16.3+, and compatibility with iOS/iPadOS 16+ and visionOS 2+. Users can easily install Companion via direct download or Homebrew, making it accessible for developers looking to enhance their MCP debugging process.