Checked Yours? MCP Server Cards, counted twice

Description and use

In October 2026, the proportion of MCP servers with valid Server Cards increased from 1.9 % to 2.7 %, and the number of servers with valid cards rose by 66 %. Most cards still lack required CORS headers, and many serve HTML instead of JSON.

Problem

Remote MCP servers rarely have valid Server Cards, limiting AI app connectivity.

Outcome

The share of hosts with a valid Server Card rose from 1.9% to 2.7% in eight days, and hosts with a valid card increased by 66%. Most cards still lack required CORS headers, and many serve HTML instead of JSON.

Workflow

• Read entire MCP Registry and keep latest version of each server with a remote endpoint.
• For each endpoint, perform read‑only GET and OPTIONS requests as a client would.
• Count responses that return a Server Card JSON, validate schema, and check CORS headers.
• Repeat the same process eight days later to capture changes.
• Use the mcp-server-card-check tool to identify failures and provide fixes.
• Publish a shared test suite for future conformance.
• Encourage server operators to run the checker and fix reported issues.

Evidence

The share of hosts with a valid card rose from 1.9% to 2.7%.

Source

The registry added 18% more hosts in eight days.

Source

Hosts with a valid card went from 352 to 586, up 66%.

Source

The checker was v0.4.1.

Source