MCP Inspector

MCP Inspector is a locally run developer tool for testing Model Context Protocol (MCP) servers. It's for developers building or checking the servers that connect AI applications to tools and data. You can inspect a local server or connect to a remote HTTP endpoint.

The browser interface provides graphical inspection with a monitoring sidebar that keeps protocol traffic visible during testing. Developers can list a server's tools, call them with test inputs, and examine the responses without working through an AI application's chat interface.

For automated checks, the command-line client produces machine-readable output for CI, shell pipelines and coding agents. An interactive terminal client supports hands-on testing when a browser isn't available or preferred. These clients share the same connection core, configuration files and OAuth state, so connections behave consistently across interfaces. They also handle both legacy and modern MCP protocol behavior.

The browser app has a local Node.js backend. Remote connections send requests to the chosen server, while OAuth state stays on disk on the machine running Inspector. Secret storage depends on the environment: machines without an OS keychain save secrets in a plaintext file by default. The tool also supports encrypted file storage or keeping secrets in memory.