{"version":"2.1.271","anchor":"mcp-server-progress-heartbeat-while-a-tool-call-runs","canonical_anchor":"mcp-serve-now-advertises-and-sends-toolslist-changed-notifi","heading":"MCP server now supports list-changed and progress notifications","tier":"notice","area":"MCP","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.271\/e\/mcp-server-progress-heartbeat-while-a-tool-call-runs","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.271","markdown":"### MCP server now supports list-changed and progress notifications\n\nclaude mcp serve now tells clients when its tool list changes and reports progress during long tool calls\n\n**What**\n\n- `claude mcp serve` now advertises a `listChanged` tools capability and sends a `tools\/list_changed` notification whenever the visible set of tools changes (for example after a policy-verdict refresh), using a new debounced watcher.\n\n- Tool call handling now reads the progress token (`_meta`\/`sendNotification`) from the incoming request and opens a progress-tracking resource for the duration of the call.\n\n- While a long-running tool call executes, the server sends periodic `notifications\/progress` messages (\"Running for Ns\") on an interval, using that progress token.\n\n**Why**\n\nMCP clients connected to Claude Code's built-in server can now stay in sync when the available tools change, and can show live progress instead of appearing stuck during slow tool calls.\n\n- Area: MCP\n- Tier: You'll notice\n- Useful: 3\/5\n- Signal: 2\/5"}