MCPJam/inspector

Testing and evaluation platform to chat, inspect, and debug MCP servers, MCP apps, and ChatGPT apps.

MCPJam Inspector – What it is

MCPJam Inspector is an open‑source platform that helps developers of MCP servers (the back‑ends that power AI‑powered assistants such as ChatGPT, Claude, Copilot, Cursor, etc.) test, debug, and evaluate their integrations. It lets you run the same server against many client configurations, inspect every JSON‑RPC and OAuth exchange, and automate regression checks in CI/CD pipelines.

Core capabilities (as described in the README)

Feature	What you can do
Playground	Interactive web UI that mimics the UI of 16 different AI clients. You can chat with a model, trigger tool calls, and see a full timeline of JSON‑RPC messages, widget renders, and OAuth flows.
OAuth Debugger	Step‑by‑step visualisation of MCP OAuth flows for several spec versions (2025‑03‑26, 2025‑06‑18, 2025‑11‑25, 2026‑07‑28). It checks Dynamic Client Registration, pre‑registration, and client‑metadata documents.
Server Debugging	Manually invoke tools, resources, templates, prompts, and elicitation flows while watching complete JSON‑RPC logs.
Skills	Load reusable “skills” (behaviour extensions) from the local filesystem or from hosted accounts, and use them in the Playground without sending code to the cloud.
Workspaces	Group servers into shared workspaces with real‑time sync so a whole team can test the same configuration together.
Evals	Define test cases that specify expected tool calls, run them across many LLMs, and collect accuracy, latency, and tool‑call metrics over time.
CLI	Terminal interface (`npx @mcpjam/inspector`) to probe servers, run OAuth checks, list tools/resources, and execute evals without a browser.
SDK	TypeScript library that lets you script inspections, take snapshots of server capabilities, and assert on tool/resource shapes from your own test suites.
CI/CD integration	Ready‑made GitHub Actions (and generic CI) steps to run conformance, end‑to‑end, eval, and OAuth checks on every pull request.

How to get started

Method	Command / Link	Notes
Hosted web app	https://app.mcpjam.com	No installation; works in any browser (HTTPS only).
Desktop app	Download from the releases page (macOS `.dmg` or Windows `.exe`).	Supports HTTP/S and local STDIO servers; no Node.js needed.
Terminal (Node)	`npx @mcpjam/inspector@latest`	Starts a local server and prints a private URL you can open in a browser.
Docker	Build from source (`docker build …`) and run with `-p 127.0.0.1:6274:6274`.	Keeps the inspector confined to localhost for security.

Typical use cases

Debugging client‑specific breakages – see why a tool call works in ChatGPT but fails in Claude.
OAuth integration testing – verify that your server complies with every MCP OAuth draft version.
Regression testing – run automated eval suites in CI to catch accuracy or latency drops before release.
Team collaboration – share a workspace link so all engineers view the same server state and test results.
Skill development – prototype reusable behaviours locally before publishing them to a hosted account.

Community & support

Docs: https://docs.mcpjam.com
Discord: https://discord.gg/JEnDtz8X6z
License: Apache 2.0 (per the repository’s LICENSE file).

Bottom line: MCPJam Inspector is a full‑stack testing and evaluation suite aimed at developers building AI‑assistant back‑ends that need to work reliably across many front‑end clients. It provides both a rich UI and programmatic interfaces to make debugging, performance tracking, and CI integration straightforward.

MCPJam/inspector