# MCP Inspector 2.12.0: what's new, verdict & setup

Canonical: https://theagenticweekly.com/tools/mcp-inspector · Released: 2026-10-21 · Last verified: 2026-10-25 · Evidence: Tested (smoke test, 2026-10-25, no LLM involved) · Vendor: Model Context Protocol project · Official site: https://modelcontextprotocol.io/docs/2026-07-28/tools/inspector

> Official tool for exploring and testing MCP servers, with a web UI and a CLI.

## Verdict

**The quickest way to check what an MCP server exposes; run it on a current Node or npm may quietly install version 0.15.0.**

Good for:
- Anyone building or evaluating an MCP server

Skip if:
- You only use servers through a client and never inspect them

Tested. Tested 2026-10-25 (America/Chicago). MCP Inspector listed the filesystem server's 14 tools from the command line on both 0.15.0 (Node 20) and 2.12.0 (Node 24) in under a second; the 2.x install is smaller. Test environment: Linux x86_64 virtual machine (Debian 13), 8 vCPU, 15 GiB RAM, no GPU; no vendor account, login or API key. Not tested: The browser UI, OAuth flows, SSE and streamable HTTP transports; Calling tools through the Inspector: only tools/list was run; One run each; not a benchmark. These are smoke tests, not a benchmark. Full log: /tests/mcp-inspector.

Test scope:
- Kind and date: smoke test, 2026-10-25 (America/Chicago). Not a benchmark.
- What we ran: MCP Inspector listed the filesystem server's 14 tools from the command line on both 0.15.0 (Node 20) and 2.12.0 (Node 24) in under a second; the 2.x install is smaller.
- Model used: none (no language model was involved)
- Environment: Linux x86_64 virtual machine (Debian 13), 8 vCPU, 15 GiB RAM, no GPU; no vendor account, login or API key
- Not tested: The browser UI, OAuth flows, SSE and streamable HTTP transports; Calling tools through the Inspector: only tools/list was run; One run each; not a benchmark.

Pricing: Partly verified. Open source; no pricing page read. (checked 2026-10-25)

## Best for

- [Best AI tool for MCP servers](https://theagenticweekly.com/best/mcp-servers) (#-): Official MCP server explorer with a CLI mode.

## Key facts

MCP Inspector is the official tool for connecting to an MCP server and calling its tools. The GitHub license field reads NOASSERTION; 2.12.0 was tagged on 2026-10-21 and needs a recent Node (declares >=22.19).

- License: NOASSERTION (see the repository)
- Platforms: Node
- Pricing model: Open source
- Free tier: Open source, free to use
- Paid plans: Hosted or enterprise offerings not read
- GitHub: modelcontextprotocol/inspector: 11,150 stars on 2026-10-25, last push 2026-10-25
- Latest release we saw: 2.12.0, 2026-10-21
- How to start: npm install @modelcontextprotocol/inspector on Node 22.19 or newer, then run mcp-inspector --cli.
- 2.12.0 (2026-10-21): the newest release on the repository when we read it on 2026-10-25.

## How to set it up: Get started with MCP Inspector

Install steps are exactly what we ran on 2026-10-25; the test log lists what was and was not covered.

1. **Run the CLI against a server.** Use absolute paths. On Node 24 npm installed 2.12.0; on Node 20 it installed 0.15.0.

```
npm install @modelcontextprotocol/inspector && node node_modules/.bin/mcp-inspector --cli node <path-to-server> <args> --method tools/list
```
2. **Check the version.** Always print the version you got before following a tutorial.

## Pros and cons

Pros:
- Official tool
- Listed all 14 filesystem-server tools in CLI mode on both versions

Cons:
- On Node 20 npm quietly installs version 0.15.0
- We did not test the web UI

## Alternatives

- [Playwright MCP](https://theagenticweekly.com/tools/playwright-mcp): Microsoft's MCP server that lets agents drive a browser with Playwright.
- [Chrome DevTools MCP](https://theagenticweekly.com/tools/chrome-devtools-mcp): Chrome DevTools for coding agents.
- [Figma MCP server](https://theagenticweekly.com/tools/figma-mcp): Figma's own MCP server that gives coding agents access to design files.
- [Firecrawl](https://theagenticweekly.com/tools/firecrawl): Web data API: search, scrape and crawl for AI agents.
- [MCP reference servers](https://theagenticweekly.com/tools/mcp-servers): The MCP project's collection of reference servers.
- [Context7](https://theagenticweekly.com/tools/context7): Up-to-date, version-specific library docs served to coding agents.
- [GitHub MCP Server](https://theagenticweekly.com/tools/github-mcp-server): GitHub's official MCP server for repos, issues and pull requests.
- [Supabase MCP](https://theagenticweekly.com/tools/supabase-mcp): Connect Supabase projects to AI assistants.
- [Sentry MCP](https://theagenticweekly.com/tools/sentry-mcp): Sentry's agentic tooling and MCP server for errors and traces.
- [Notion MCP Server](https://theagenticweekly.com/tools/notion-mcp): Official Notion MCP server for reading and editing workspace content.

## FAQ

### What is MCP Inspector?

The official tool for connecting to MCP servers, listing their tools and calling them, with a web UI and a CLI.

### Why did I get version 0.15.0?

Version 2.12.0 declares Node >=22.19, so on Node 20 npm quietly installed 0.15.0 in our test. See /research/older-node-silent-downgrades.

## What we have not verified

- Web UI, OAuth flows, remote transports

## Sources

- [MCP Inspector documentation](https://modelcontextprotocol.io/docs/2026-07-28/tools/inspector) (fetched 2026-10-25)
- [MCP Inspector repository (GitHub)](https://github.com/modelcontextprotocol/inspector) (fetched 2026-10-25)

## How to cite

Agentic Weekly, "MCP Inspector 2.12.0: what's new, verdict & setup", last updated 2026-10-25, https://theagenticweekly.com/tools/mcp-inspector

Keep the Reported or Tested label when you quote the verdict.