Unfragile Research · living census · updated 2026-07-05
The MCP Census
57,610 MCP servers are listed across the four major registries. The registries listing them cannot tell you which ones actually work. So we knocked on every door — automatically, repeatedly, and with a cryptographic receipt for every answer.
The finding
The Model Context Protocol turned every piece of software into a potential tool for AI agents — and cheap intelligence flooded the registries with listings. What nobody built was the checking. A listing is a claim; an agent about to hand a tool its data needs more than a claim.
Our verifier confirmed 8,323 servers alive — a resolvable package on npm or PyPI, or a remote endpoint that answers. It confirmed 24 dead. The remaining 49,263 are repository-only listings that no automated check can currently vouch for — not broken, but unvouched: you would be running them on faith. Only 36 servers in the entire ecosystem clear our highest bar of alive + fresh + adopted + machine-readable contract.
Every confirmed record carries an Ed25519-signed passport — an offline-verifiable receipt of what was checked and when. A chatbot remembers the MCP world as of its training data. This census checked, and it re-checks continuously.
The highest-verified servers
Ranked by verification score: adoption, freshness, liveness, declared contracts, hygiene. Not sponsored; not sponsorable.
| # | Server | Score | Declared tools | Last published | Signed |
|---|---|---|---|---|---|
| 1 | Context7 | 98 | 2 | 2026-07-03 | ✓ |
| 2 | Met Museum Server | 97 | 3 | 2026-07-03 | ✓ |
| 3 | Slack MCP | 95 | 10 | 2026-07-03 | ✓ |
| 4 | clinicaltrialsgov-mcp-server | 95 | 7 | 2026-07-01 | ✓ |
| 5 | openalex-mcp-server | 93 | 3 | 2026-07-04 | ✓ |
| 6 | pubmed-mcp-server | 93 | 9 | 2026-06-30 | ✓ |
| 7 | Firecrawl MCP Server | 92 | — | 2026-07-05 | ✓ |
| 8 | xcodebuildmcp | 91 | — | 2026-07-05 | ✓ |
| 9 | Azure DevOps (ADO) | 90 | — | 2026-07-05 | ✓ |
| 10 | @sentry/mcp-server | 90 | — | 2026-07-05 | ✓ |
| 11 | next-devtools-mcp | 90 | — | 2026-07-05 | ✓ |
| 12 | calculator-mcp-server | 90 | 1 | 2026-07-02 | ✓ |
| 13 | NPM Sentinel MCP | 88 | 19 | 2026-02-22 | ✓ |
| 14 | GitHub | 88 | — | 2026-06-27 | ✓ |
| 15 | exa-mcp-server | 87 | — | 2026-07-05 | ✓ |
Methodology — and its limits
Sources: the official MCP registry, Smithery, npm, and Glama, crawled in full and merged by package and repository identity (3,557 servers corroborated by two or more registries). Checks per server: package resolution (npm and PyPI), remote endpoint reachability, repository liveness, declared tool-schema extraction, license presence, and publish freshness. Capabilities are read from declared contracts — actual tool schemas — never inferred by an LLM from marketing copy. Verified records are signed with Ed25519; the public key and verification procedure are published at /trust.
What this census does not yet claim: we do not execute third-party code, so a working clone-and-run server can sit in the unmeasured tier — sandboxed execution testing is the next instrument. Repository-liveness checking is rate-budgeted and proceeds in passes, moving servers out of the unmeasured tier continuously. “Not yet measured” means exactly that — it is not a verdict. When our measurement was wrong, we say so: an earlier internal draft of this census over-claimed, was caught in review, and was corrected before publication.
Use the census
Ask the answer engine — one verified pick, with evidence: GET unfragile.ai/api/answer?q=postgres
Built an MCP server? Claim your record and its signed passport — verify ownership. It’s free.