long-running-tools

The MCP Tasks extension (io.modelcontextprotocol/tasks, spec 2026-07-28, SEP-2663) lets a server answer tools/call with a durable task handle instead of a result. The client polls tasks/get, answers mid-flight questions with tasks/update, and can cancel or reconnect. Here is the wire protocol, what changed from the experimental 2025-11-25 version, when a task is worth it, and a working server and client checked against @modelcontextprotocol/ext-tasks 0.2.2.