modelcontextprotocol/inspector

What it solves

MCP Inspector is a developer tool designed to help developers build and debug Model Context Protocol (MCP) servers. It provides a way to inspect, test, and verify the behavior of these servers without needing to integrate them into a full AI agent or client application first.

How it works

The tool provides three different interfaces for interacting with an MCP server:

• Web UI: A single-page application built with React and Mantine that allows for visual inspection and interaction.
• CLI: A scriptable command-line interface for automation, CI/CD pipelines, and fast feedback loops.
• TUI: An interactive terminal user interface built with Ink.

All three interfaces share a common core logic (@inspector/core) that manages the connection to the MCP server, handles the request/response lifecycle, and manages state. It supports various connection methods, including stdio and HTTP, and can bet configured via JSON files or command-line flags.

Who it’s for

Developers creating MCP servers who need a tool to verify that their tools, resources, and prompts are correctly exposed and functioning as expected.

Highlights

• Three Interface Options: Choose between a full web browser experience, a scriptable CLI, or an interactive TUI.
• Cores Shared Logic: Ensures consistent behavior across all three clients.
• Comprehensive Testing Suite: Includes composable test servers and presets to simulate various protocol features like OAuth, pagination, and structured output.
• Modern Protocol Support: Supports the latest protocol era (2026-07-28) including features like MRTR (Multi-Round Trip Request) and standardized HTTP headers.
• App Review Capabilities: Includes a specific workflow for reviewing MCP Apps, including a sandbox iframe for rendering widgets.