I built ProtocolProbe on my own to read the official MCP registry and public package records. This post is one question: when a registry entry links to a repository, does the link open?
Why ask
The registry checks that a repository URL is well-formed. As far as I read its source (2026-10-06), it does not fetch the URL, and it checks a package once, at publish time. So a link that worked at publish can stop working later, and a link that never worked is still accepted. I have not re-run that source read since.
Method
For every registry entry that links to a GitHub repository, I called GitHub's public repository API and recorded the HTTP status. Public records only. I did not run or call any MCP server.
Registry snapshot: 2026-10-04. Lookups: 2026-10-06.
Numbers
| What | Count | Of | Share |
|---|---|---|---|
| Entries whose linked repo returns HTTP 404 | 4,298 | 38,977 registry entries | 11.0% |
| Same, counted by publisher | 2,594 | 23,016 publishers | 11.3% |
| Same, among entries that link to GitHub | 4,298 | 28,743 | 15% |
| Linked repo is archived (read-only) | 309 | 24,256 entries with a reachable repo | 1.3% |
What a 404 means
GitHub returns 404 for a repository that is missing or private. From outside I can't tell which. It could be a rename, a deletion, a private repo or a typo. It is not a judgement on the publisher, and the registry never promised to re-check.
Limits
- Figures are from 2026-10-06, not live.
- GitHub links only; other hosts are not counted.
- Counting by publisher is shown next to entries because a few publishers own many entries.
- No monthly re-check has run yet, so I can't say how these numbers move over time.
Data and method
- Page with the figures and sources: https://protocolprobe.com/mcp/reports
- Dataset (Zenodo): https://doi.org/10.5281/zenodo.23386799
If you see a flaw in the method, tell me in the comments.
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