mcp-go implements MCP spec 2025-11-25 with task-enhanced tools

mcp-go is a Go implementation of the Model Context Protocol, used to connect LLM applications with external data sources and tools. It implements MCP spec 2025-11-25 and remains backward compatible with 2025-06-18, 2025-03-26, and 2024-11-05. Core capabilities include servers, resources, tools, and prompts; resources support static URIs and dynamic templates, and tools can run either synchronously or as task-enhanced async operations. Task-enhanced tools offer three modes: TaskSupportForbidden, TaskSupportOptional, and TaskSupportRequired. In async mode the server immediately returns a task ID, the tool runs in the background, clients poll results via tasks/result, and the server sends status notifications on completion. For Go developers writing MCP servers, async task mode keeps long-running operations from blocking or timing out; WithMaxConcurrentTasks limits the number of tasks in the working state, with new task creation requests failing once the cap is reached. Completed, failed, or canceled tasks don't count toward the limit, and unset or zero means no limit. Additional features such as OAuth-protected resource metadata, session management, per-session tools, tool filtering, request hooks, and tool-handling middleware give teams building full MCP services infrastructure from authentication to tool governance. The project is still in active development: core features are usable, while some advanced capabilities are still in progress.