/sse endpoint for bidirectional MCP communication.curl --location 'https://api.dufrei.com/messages' \
--header 'x-api-key: <api-key>' \
--header 'Content-Type: application/json' \
--data '{
"jsonrpc": "2.0",
"method": "getFinancialDocs",
"params": {},
"id": "req-001"
}'{"error":{"code":400,"message":"Invalid query parameter","details":["'limit' must be an integer between 1 and 100"]}}