Why does npx @modelcontextprotocol/inspector fail with 'mcp-inspector: command not found' after 0.10.0?
After upgrading the MCP Inspector to 0.10.0, running npx @modelcontextprotocol/inspector fails with 'sh: mcp-inspector: command not found' on macOS, Windows, and WSL. The same command worked on 0.9.0. The published npm package appeared to be missing most of its files.
Originally asked on GitHub: https://github.com/modelcontextprotocol/inspector/issues/326
5 answers
The 0.10.0 package on npm was incomplete: the registry copy only contained the client folder, package.json, and README, so no
mcp-inspectorbinary was installed. A maintainer confirmed that the source archive and a publish dry run contained the full package, and said the publishing step was fixed in 0.10.2.Workarounds reported in the thread:
- Pin the last working version and run it directly:
npx @modelcontextprotocol/inspector@0.9.0- On Windows PowerShell, Git Bash, cmd, and WSL, the same pinned command worked for several users.
If you hit this, check which version npx resolved, then use 0.10.2 or later. One later report of the same error on 0.16.1 could not be reproduced by a maintainer, who said the current release worked for them. If you see this again, pinning a known-good version is the quickest workaround.
General advice: pinning an exact version in scripts (for example,
@modelcontextprotocol/inspector@0.10.2) avoids picking up a broken publish automatically.Did this work for you?What @tadhgboyle tried on GitHub (Didn't work)
Ran npx @modelcontextprotocol/inspector after upgrading to 0.10.0 and got 'mcp-inspector: command not found'. The command had worked before the upgrade.
Source: https://github.com/modelcontextprotocol/inspector/issues/326 (opens external site)
Did this work for you?What @localden tried on GitHub (Worked)
Ran npx @modelcontextprotocol/inspector@0.9.0 in PowerShell instead of the unpinned command after the failure.
Did this work for you?What @cliffhall tried on GitHub (Outcome unclear)
A maintainer compared the npm package contents with an npm publish dry run and the GitHub release archive. The npm package was missing files, so the publish step was identified as the cause.
Did this work for you?What @cliffhall tried on GitHub (Worked)
A maintainer said the publishing issue was fixed and the next release, 0.10.2, would include the fix.
Did this work for you?
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