Adding Gmail and HEY With Custom Ruby Tools

Apple Mail was reachable over MCP, so Part 1 attached it with the mcp macro and never wrote a line of integration code. Gmail and HEY are different. Gmail I want to read over IMAP with an app password, without OAuth or a Google SDK. HEY has a command line client and no public API. Neither speaks MCP. For those, Nexo uses its other tool shape: a plain RubyLLM::Tool . You write a small Ruby class…