Model Context Protocol (MCP) is an open standard for plugging external context and actions into a coding agent: a small server exposes tools or data, your agent connects to it, and suddenly the agent can read your database schema or your internal API instead of guessing. The hype says it changes everything. The reality is narrower - and more useful.

Four uses that pay off

  1. Live docs for niche libraries. Agents hallucinate APIs for anything underrepresented in training data. A docs MCP server for your obscure SDK means generated calls match the real interface. Highest payoff, lowest risk.
  2. Read-only database access. Schema plus a sample of real rows turns “write me the query” from a guessing game into a verified artifact. Read-only credentials are the whole trick - never hand the agent write access.
  3. Your design system. Expose component names, props and tokens so the agent assembles UI from your library instead of inventing a plausible-but-nonexistent <Button variant="primary-ghost">.
  4. Internal API surface. Point the agent at your OpenAPI spec or endpoint registry before it writes a client. It stops fabricating routes and payloads.

The pattern: MCP shines when the truth is live, structured, and under-memorized by models.

Two uses that don’t

  1. Wrapping what you could paste. A 60-line style guide does not need a server - it needs two lines in AGENTS.md. Every server you run is maintenance; spend that budget where a static file can’t keep up.
  2. Broad write access. “The agent can deploy / delete / email” is not a workflow, it’s an incident waiting for a vague prompt. Write actions belong behind human review, full stop.

Start in 30 minutes

  1. Pick your single most-hallucinated source of truth (docs, schema, design tokens).
  2. Find the maintained MCP server for it - most popular sources already have one; check your agent’s server directory.
  3. Configure it read-only with scoped credentials.
  4. Run one real task against it and compare output with your usual guessing baseline.

If the difference isn’t obvious on task one, drop it and revisit in a quarter. MCP is a scalpel, not a diet - add servers one at a time, each tied to a mistake you keep correcting by hand.