This is a submission for DEV's Summer Bug Smash: Clear the Lineup powered by Sentry.
Project Overview
I've been working on a Tokyo public transit MCP server for a while (see the previous posts in the series). Recently, I started experimenting with adding a SKILL.md to see whether giving the agent more structured guidance would improve its behavior and output.
Instead of treating this as simply another feature, I turned the project into a small debugging and experimentation exercise of How MCP tools and Skills work together, and adding another layer of guidance actually makes an agent better (or worse).
At a high level, MCP provides the agent with capabilities and tools, while a Skill provides task-specific guidance for when and how those capabilities should be used.
