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The MCP endpoint speaks Streamable HTTP, with sessions and a notification stream

The hosted MCP endpoint now implements the standard Streamable HTTP transport, so a client can hold a session and open a stream that tells it what changed, while plain JSON-RPC POST keeps working exactly as before.

The MCP endpoint at https://api.last-price.ai/api/mcp/rpc now implements the Model Context Protocol Streamable HTTP transport (revision 2025-11-25). Any MCP client that speaks it can connect with just the URL and, optionally, your key in x-api-key or Authorization: Bearer. Clients that POST plain JSON-RPC, as before, see no change.

  • Sessions. initialize returns an Mcp-Session-Id header. Sending it back is optional. The id is a signed token that every server works with, so you can send it on every call. It stays valid for 24 hours and belongs to whoever opened it: a refreshed token or a rotated key for the same workspace and agent keeps it. You get 404 only for an altered id, an expired one, or one opened by someone else; then send initialize again. Without the header every request is served statelessly.
  • A notification stream. GET with Accept: text/event-stream returns the newest release notes written for agents (notifications/lastprice/changelog, up to three entries with date, title, summary and link) and closes at once, with a hint to come back in five minutes.
  • Streamed replies when you ask. A POST answers over the stream format only when Accept lists text/event-stream without JSON, or when a tool call carries a progress token; then a progress notification comes first. Otherwise the reply is JSON, as before.
  • Instructions. initialize now returns short instructions: what the server does, and a pointer to this changelog.
  • Sessions end on their own. DELETE answers 405: there is nothing stored to end, so simply stop sending the id.

The discovery document at /.well-known/mcp.json advertises transport: "streamable-http", lists the older http+jsonrpc value alongside it, and describes the session rules, including sessions: "stateless". A request from a web page on another origin is refused with 403, and an unsupported MCP-Protocol-Version header with 400. Questions: support@last-price.ai.