Streamable HTTP is the current standard transport for the Model Context Protocol (MCP). It replaced the older HTTP + SSE transport, and it is what modern clients like Claude and Cursor use to talk to an MCP server.
An MCP server exposes a single HTTP endpoint. A client POSTs JSON-RPC messages to it — initialize, tools/list, tools/call — and the server responds, either with a plain JSON response or by upgrading to a Server-Sent Events (SSE) stream for long-running requests.
| Method | Purpose |
|---|---|
initialize | Handshake — agree on protocol version and capabilities |
tools/list | Discover which tools the server exposes |
tools/call | Invoke a tool with arguments |
ping | Keep-alive / liveness check |
You can verify any MCP server by hand. First the handshake:
curl -X POST https://mcp.xn--5kvtwv52d.com/mcp/gateway \
-H "Content-Type: application/json" \
-d '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"probe","version":"1"}}}'
Then list the tools:
curl -X POST https://mcp.xn--5kvtwv52d.com/mcp/gateway \
-H "Content-Type: application/json" \
-d '{"jsonrpc":"2.0","id":2,"method":"tools/list","params":{}}'
If you build or host an MCP server, you want Streamable HTTP because it is what current clients expect, and it works cleanly behind proxies and through serverless functions. A hosted MCP gateway gives you a ready-made Streamable HTTP endpoint — so you don't have to implement the transport yourself.
Best MCP gateway · Host an API as MCP · Cross-agent settlement