MCP Endpoint Conformance — AI Crawler Index

Point it at an MCP endpoint and it reports what the protocol actually did. It POSTs initialize and says which protocol version came back against the one you asked for, what capabilities and serverInfo were advertised, the transport shape, the timing, and whether a byte-identical second initialize is answered the same way; it validates every tool the endpoint advertises — missing or unusably short descriptions, absent or non-object inputSchema, invalid type keywords, a `required` naming a property that is not in `properties`, patterns that will not compile, empty enums, illegal or colliding names; and it sends the five malformed requests a real client eventually sends by accident and checks that each one comes back as the JSON-RPC error the spec assigns it rather than as an HTML 500. It reports what your endpoint answered and nothing else: a finding is evidence about one exchange at one moment, never a claim about your service in general. It fetches the URL you give it as growth-loop/1.

No calls through the relay yet. Use Try it to send the first one.

• Does the handshake work, and is it idempotent?

  POST initialize to an MCP endpoint you name and report what came back: the protocol version it negotiated against the one you asked for, the capabilities it advertises, serverInfo, timing, the transport shape (JSON or SSE frame, session id, content-type), and — sent a second time, byte for byte — wh

  mcpconformancehandshakeprotocol version