mcpreflight (formerly mcpdoctor) is an open-source, read-only preflight checker for MCP servers and x402 payment endpoints. It runs an MCP initialize handshake and tools/list validation without calling any tools. Install-free usage: npx @eidonze/mcpreflight schema .

Is mcpreflight a security audit?

No. It validates protocol conformance and tool schema quality, not runtime behavior or code safety. A PASS means the observed responses matched the checks in that version.

How many MCP servers fail a basic check?

In the weekly scan of 9,991 remote registry endpoints (October 2026), 4,879 passed a clean anonymous handshake, 5,069 gave no anonymous response, and 43 failed outright. Full data on the State of MCP report page.

mcpreflight — read-only MCP preflight checks & x402 inspector

01Three ways to run it

Same engine, same read-only guarantees, wherever you need it.

CLI

One command against any endpoint. Deterministic PASS/FAIL, exact failing step, JSON or markdown output.

CLI guide

GitHub Action

mcp-trust-check on every pull request. Fails the build when a registered server stops completing a clean handshake.

CI guide

MCP server mode

Expose schema_check and x402_inspect as MCP tools inside your own agent stack.

README

02What you can check

Every check is reproducible with one command and documented with its limits.

CHK·1

Schema check

initialize + tools/list, tool names, descriptions, input/output JSON schemas, required fields. 46,216 property-level findings logged across the registry.

Schema guide

CHK·2

x402 inspector

HTTP 402 challenge shape, payment documents, accepts[], discovery manifests, latency and response digest, all without paying.

x402 guide

CHK·3

Trust Directory

Per-server reports, status badges and JSON APIs for 9,991 official-registry endpoints. Re-scanned every Monday.

Browse directory

CHK·4

Agent Evidence

ERC-8004 on-chain registrations cross-checked against their declared MCP endpoints: 40 endpoints, five-level verdicts, reasons and timestamps.

Sample report

03State of MCP — October 2026

48.8% passed 50.7% no anonymous response 0.4% failed outright

4,879passed a clean handshake

5,069gave no anonymous response

43failed outright

115passed last week, unknown this week

Of 9,991 remote endpoints in the official registry. Plus a second finding: all 213 Smithery-registered entries refused anonymous handshakes. Full report, method and limits →

04Guides

05Boundaries

Honest limits. mcpreflight never calls MCP tools, accepts credentials, executes server commands, signs or settles payments, or proves delivery. PASS is a deterministic observed-check result for the checks in that version — not a security certification and not a trust score.

Know an MCP server works before your agent depends on it.