Valid JSON, not JSON-RPC

not-json-rpc · Transport & framing

Endpoint (Streamable HTTP)

https://chaos-mcp.thomascdnns.com/s/not-json-rpc/mcp

On the wire — recorded from a real request

Symptom

what you'll observe

Client says 'invalid response' / missing jsonrpc field, though the body parses as JSON.

Cause

what this reproduces

Server returns its own REST-style envelope and forgot the JSON-RPC 2.0 wrapper.

Fix

how you'd resolve it

Wrap every response in {"jsonrpc":"2.0","id":<id>,"result":...}.

Try it with curl

bash

curl -sS -X POST \
  https://chaos-mcp.thomascdnns.com/s/not-json-rpc/mcp \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json' \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "initialize",
    "params": {
      "protocolVersion": "2024-11-05",
      "capabilities": {},
      "clientInfo": {"name": "curl", "version": "1"}
    }
  }'