We audited 920 public MCP servers — 80% returned no real content

Name: Public MCP server liveness census (2026-06)
Creator: SaSame
License: https://opendatacommons.org/licenses/by/1-0/

Open data + reproducible method · 2026-06-18 · SaSame

We index public MCP (Model Context Protocol) servers from the registries agents are told to discover tools from, and probe each one with a polite, GET-only liveness check. This is the honest result across 920 distinct public MCP servers.

20.3% returned real content. 79.7% did not.

Result	Count	Share
Returned real content to a polite probe	187	20.3%
Returned nothing usable (error / empty / dead / placeholder)	733	79.7%
Total audited (distinct servers)	920	100%

"Registered" is not "reachable." A server listed in a registry but returning nothing to a probe is invisible to the agents that would call it.

Coarse quality grade (a separate axis from the content check): A 110 · B 140 · C 644 · D 26.

The full per-server data is open: mcp-census-2026-06.csv (url, grade, returns_real_content, audited_at for all 920).

What the check means (so you can falsify it)

Population: public MCP servers indexed from public registries. The 920 is the audited subset of a larger indexed ledger.
Probe: a single polite GET-only request. We never authenticate, never pay, and skip priced/x402 endpoints. Rate-limited (~1 / 1.5s).
returns_real_content = true means a non-trivial real response body at audit time — not an error, not empty, not a placeholder.

Honest caveats (read before citing): This is a snapshot (2026-06-18). Some servers may have been temporarily down, behind auth we did not pass, or expecting a POST/JSON-RPC initialize handshake that a liveness GET does not perform — so this is "no real content to a polite GET," not a claim that 80% are permanently dead. But it is what a discovery crawler or a casual agent sees. The grade is our own heuristic, not a standard. And we have an interest here — we help with MCP discoverability — which is exactly why the raw data and method are open. Re-run it and tell us if we're wrong.

If your MCP server is registered but isn't getting called, that is the exact thing we diagnose and fix at SaSame. The free check is real; the paid object is the executed fix plus proof that agents now call your tools.

SaSame · srl-sasame.com · data CC-BY · method reproducible (see the report repo)