Agentic WeeklyGet the weekly
Model Context Protocol project2.12.0Tested (smoke test)

MCP Inspector: what’s new in 2.12.0 and our verdict

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

Official site

Release Ruler for MCP Inspector: marked at its Tested release date on the timeline of every AI model we track.

At a glance

Evidence
Tested (smoke test)
Released
Oct 21, 2026
Last verified
Oct 25, 2026
Pricing
Partly verified
Best for
MCP servers

Evidence and ranking

Evidence behind this verdict

  1. Sources read2 cited sources, latest fetched Oct 25, 2026. (done)
  2. Facts re-checkedLast verified Oct 25, 2026. (done)
  3. Run by usSmoke test on Oct 25, 2026 (scope below). (done)

Passed Test log result: Passed. Read the log

Where we rank it (editorial)

Listed here but not yet ranked. Ranks are editorial picks, not benchmark scores.

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

Our 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.

Evidence
Tested (smoke test, 2026-10-25, no LLM involved). A smoke test is 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.
Date
(America/Chicago)

Best for

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 and comparisons

  • Playwright MCP: Microsoft's MCP server that lets agents drive a browser with Playwright.
  • Chrome DevTools MCP: Chrome DevTools for coding agents.
  • Figma MCP server: Figma's own MCP server that gives coding agents access to design files.
  • Firecrawl: Web data API: search, scrape and crawl for AI agents.

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

Last verified · Agentic Weekly

How to cite this page

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 a verdict. Plain-text version: https://theagenticweekly.com/tools/mcp-inspector.md. More for AI assistants: /ai, /tools.json, /llms.txt.