docs: add a one-page MCP setup for Claude and Codex

Steps people and coding agents can follow to run the app, add the MCP
server to Claude Code, Claude Desktop, the Codex CLI and the Codex and
ChatGPT desktop apps, and check it works, linked from the README and the
tools guide.

docs/TOOLS.md

@@ -4,6 +4,8 @@ Tools answer questions from God's Eye View data for language-model clients.
 They are defined once and exposed through adapters: the Model Context Protocol
 (MCP) and function calling, which voice uses.
 
+To use them from Claude or Codex, see [MCP setup](MCP_SETUP.md).
+
 ## Layers
 
 | Owner                | Responsibility                                                                                    |