A subagent keeps work out of your context; an MCP server does the opposite job, it reaches *out* of Claude Code to systems you didn't build. This episode is the rung where Claude Code stops being a smart thing in your terminal and starts touching your real database, a real browser, your GitHub repos, and your error tracker. We cover what the [Model Context Protocol](https://www.anthropic.com/news/model-context-protocol) is (Anthropic's open "USB-C for AI," the N-by-M integration problem, the host/client/server roles, and the three things a server exposes: tools, resources, and prompts), plus the adoption wave through OpenAI, Google, and Microsoft. Then the hands-on part: the two transports you actually use (local stdio and remote HTTP, with SSE deprecated), the `claude mcp add` command and the load-bearing double-dash rule, and the three config scopes, local, project, and user, including which file gets committed to git and why project-scoped servers trigger an approval prompt. Worked examples a web dev wires up: the official [Playwright browser server](https://github.com/microsoft/playwright-mcp), a read-only Postgres/Supabase server, the remote GitHub server, Sentry over OAuth, and Context7 for live docs. We cover OAuth versus header auth and the environment-variable expansion pattern that keeps secrets out of a committed config. The pitfall gets real time: tool-surface bloat. Real numbers on how MCP tool definitions eat the context window (GitHub's server alone is ~17.6k tokens), how tool-selection accuracy collapses when the menu is too long, how to recognize it, and the deferred tool-loading fix that went GA in 2026. Plus the security half, Simon Willison's [lethal trifecta](https://simonwillison.net/2025/Jun/16/the-lethal-trifecta/) and why least privilege and that approval prompt matter. Closing contrast: MCP adds capabilities, skills add knowledge, subagents add workers, hooks add guardrails. Docs: [Claude Code MCP](https://code.claude.com/docs/en/mcp).