Day 5 · Mon, Oct 5, 2026

MCPs for Hermes

Two-panel recap: Day 4 grounded Hermes in real data with RAG; Day 5's goal is connecting Hermes to real external systems over MCP

Day 4 taught Hermes to know things by grounding it in real documents through RAG — but that was still a read-only, passive skill. Today is about teaching Hermes to reach things: a clock, a filesystem, a search engine, a database, all through one standard protocol called MCP. By the end of the session, Hermes will answer questions it could only get right by actually calling a tool, not by knowing or guessing the answer in advance.

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The Model Context Protocol (MCP) is how Hermes reaches out to external systems — a time server, a filesystem, a search engine, a database — as first-class tools rather than one-off custom code. Today is about registering real MCP servers and confirming Hermes actually calls them instead of guessing the answer itself.

Objectives

Understand what an MCP server is and why Hermes talks to it over a standard protocol
Register an MCP server with hermes mcp add
Force a question that can only be answered correctly by actually calling the tool
Diagnose a broken MCP registration (bad path, wrong flag order) when it doesn't work

Lab: register and exercise an MCP server

Register the time MCP server — a small, dependency-light server that's a good first target because a wrong answer is easy to spot:

$ hermes mcp add mcp-time --command uvx --args mcp-server-time

If uvxisn't on Hermes's PATH, register it with an absolute path instead — a real gotcha we hit in an earlier live session:

$ hermes mcp add mcp-time --command /home/jay/.local/bin/uvx --args --with 'mcp<1.10' mcp-server-time

Then ask a question that requires the tool, not a guess, to answer correctly:

$ hermes -z "What time is it right now in Calgary and in Bengaluru? Use your MCP time tool, do not guess." --cli --yolo

Session notes: to be filled in after the live session on Oct 5, 2026 — which MCP servers we registered live and the real tool-call output.