MCPJam Inspector is a comprehensive testing and debugging tool designed for developers working with Model Context Protocol (MCP) servers and applications. It offers an intuitive interface to test MCP servers, send requests, analyze responses, and debug protocol interactions in real-time. By providing a local development environment, MCPJam Inspector eliminates the need for external tunneling services or subscriptions, streamlining the development process.
Key Features and Functionality:
- ChatGPT Apps SDK Support: Enables local development for ChatGPT Apps SDK, offering full support for the `window.openai` API, including functionalities like `widgetState`, `callTool`, `structuredContent`, and more. This allows developers to build and test applications without requiring external services.
- MCP Apps (Claude) Development: Facilitates local development for MCP Apps (SEP-1865), supporting all JSON-RPC message types such as `tools/call`, `ui/initialize`, `ui/message`, and others, ensuring comprehensive testing capabilities.
- OAuth Debugger: Provides a detailed debugging environment for MCP server’s OAuth implementations, allowing developers to visually inspect every network message and support all protocol versions, including client pre-registration, Dynamic Client Registration (DCR), and Client-Initiated Metadata Discovery (CIMD).
- LLM Playground: Offers a platform to interact with MCP servers using various Large Language Models (LLMs), including frontier models like GPT-5 and Claude Sonnet, or the option to integrate custom API keys. This feature supports both ChatGPT apps and MCP Apps, enabling thorough testing across different models.
- MCP Server Debugging: Allows connection to and testing of any MCP server, whether local or remote. Developers can manually invoke MCP tools, resources, resource templates, and elicitation flows, with access to all JSON-RPC logs, supporting all features from the official MCP inspector.
- Server Information Display: Provides comprehensive server details, including icons, version, capabilities, instructions, and ChatGPT widget metadata exposed by the server, aiding in better understanding and management of server configurations.
Primary Value and Problem Solving:
MCPJam Inspector addresses the challenges developers face in testing and debugging MCP servers and applications by offering a unified, local-first platform. It eliminates the need for external tunneling services or subscriptions, reducing setup complexity and potential security risks. By supporting a wide range of protocols and providing detailed debugging tools, it ensures that developers can efficiently build, test, and deploy MCP servers and applications with confidence. The inclusion of features like the OAuth Debugger and LLM Playground further enhances the development experience, allowing for thorough testing and validation of applications across different environments and models.
