`sh: mcp-inspector: command not found` after upgrading to v0.10.0

[tadhgboyle]

Describe the bug
After upgrading to the newest 0.10.0 release, running the command (which worked right before the upgrade) is now failing for me:

npx @modelcontextprotocol/inspector

To Reproduce
Steps to reproduce the behavior:

1. Upgrade to latest version
2. Run command
3. See issue

Expected behavior
I expected it should boot up as per normal

Logs
This is all I see now:

[shipurjan]

I have the same problem

Windows 11 24H2

The problem occurs in Git bash, cmd, WSL

0.9.0 works

$ npx @modelcontextprotocol/inspector node
'mcp-inspector' is not recognized as an internal or external command,
operable program or batch file.

$ npx @modelcontextprotocol/inspector@0.9.0 node
Need to install the following packages:
@modelcontextprotocol/inspector@0.9.0
Ok to proceed? (y) y

Starting MCP inspector...
⚙️ Proxy server listening on port 6277
🔍 MCP Inspector is up and running at http://127.0.0.1:6274 🚀

[localden]

Same problem on Windows boxes for us, in PowerShell. Have to downgrade to 0.9.0:

npx @modelcontextprotocol/inspector@0.9.0

[cpang-pallas]

Same problem in MacOS Sequoia 15.3.2, running npx @modelcontextprotocol/inspector in bash results in sh: mcp-inspector: command not found

[cpang-pallas]

Same problem on Windows boxes for us, in PowerShell. Have to downgrade to 0.9.0:

npx @modelcontextprotocol/inspector@0.9.0

0.9.0 works for me as well.

[johnkors]

Well, that's hours I'll never get back.. :D Same issue here. Pinning versions from now on..

[jonigl]

It seem there's an issue on this new version

Need to install the following packages:
@modelcontextprotocol/inspector@0.10.0
Ok to proceed? (y) y

sh: mcp-inspector: command not found

In the meantime I run the inspector by explicitly selecting previous version (for those who may be experiencing the same issue)

npx @modelcontextprotocol/inspector@0.9.0

I also added this comment on the PR
#324 (comment)

[cliffhall]

What's going on?

• Something seems to have gone wrong in the final npm publishing step.
• All the code is in the downloadable archive for the release.
• An npm publish --dry-run on main shows the complete package as what should be published.
• The published package on npm is incomplete.

Problem is an incomplete package on NPM

• When I look at the code in the code tab for the release on NPM, I only see the client folder, package.json, README.

NPM Publish Dry Run contains what should be there

• When I try npm publish dry-run I see all the files that should be published to the 0.10.0 release on NPM.

Source code in Github Release contains what should be there

• When I download the source code zip on the Github release page I see all the contents

[jpmcb]

This also impacts servers being built from SDKs in dev mode. For example, in my Python based SDK:

❯ mcp dev main.py
sh: mcp-inspector: command not found
[04/17/25 15:25:27] ERROR    Dev server failed 

---

Something seems to have gone wrong in the final npm publishing step.

How are NPM packages currently being published? From internal Anthropic pipelines? Off someone's laptop?

I'd recommend lifting and shifting those processes to the modelcontextprotocol org in this repo under a GitHub action for full community visibility and validation https://docs.github.com/en/actions/use-cases-and-examples/publishing-packages/publishing-nodejs-packages#publishing-packages-to-the-npm-registry

A very simple NPM publish action can be triggered on new release:

name: Publish Package to NPM
on:
  release:
    types: [published]
jobs:
  build:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      id-token: write
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: '20.x'
          registry-url: 'https://registry.npmjs.org'
      - run: npm publish --provenance --access public
        env:
          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}

[cliffhall]

How are NPM packages currently being published? From internal Anthropic pipelines? Off someone's laptop?

I'm personally not certain about the final publish step. I created the release tag (which has everything that should be on npm right now) but after that, an Anthropic core team member needs to publish. I was careful to check the output of a publishing dry run, because we have a new sub-package that I wanted to be certain would be included. I can only speculate it was published without first building.

I'd recommend lifting and shifting those processes to the modelcontextprotocol org in this repo under a GitHub action for full community visibility and validation https://docs.github.com/en/actions/use-cases-and-examples/publishing-packages/publishing-nodejs-packages#publishing-packages-to-the-npm-registry

💯

[cliffhall]

Ok, everyone. 0.10.2 is your next release. We found a chink in the publishing armor and got that sorted.