Teknium d5d22fe7ba feat(mcp): dynamic tool discovery via notifications/tools/list_changed (#3812) ...

When a connected MCP server sends a ToolListChangedNotification (per the
MCP spec), Hermes now automatically re-fetches the tool list, deregisters
removed tools, and registers new ones — without requiring a restart.

This enables MCP servers with dynamic toolsets (e.g. GitHub MCP with
GITHUB_DYNAMIC_TOOLSETS=1) to add/remove tools at runtime.

Changes:
- registry.py: add ToolRegistry.deregister() for nuke-and-repave refresh
- mcp_tool.py: extract _register_server_tools() from
  _discover_and_register_server() as a shared helper for both initial
  discovery and dynamic refresh
- mcp_tool.py: add _make_message_handler() and _refresh_tools() on
  MCPServerTask, wired into all 3 ClientSession sites (stdio, new HTTP,
  deprecated HTTP)
- Graceful degradation: silently falls back to static discovery when the
  MCP SDK lacks notification types or message_handler support
- 8 new tests covering registration, refresh, handler dispatch, and
  deregister

Salvaged from PR #1794 by shivvor2.

2026-03-29 15:52:54 -07:00

76 KiB

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