Start with current documentation. This is where small mistakes compound: the agent writes code for an old option name, a deprecated initialization path, or an example from the wrong major version. Context7 exists for exactly that gap.
Then add repository context if your work starts from issues, pull requests, reviews, or releases. Add database or browser tools when the task truly crosses those boundaries. Add memory only when you have decisions worth carrying between sessions.
A useful rule: if a server does not help the agent decide, verify, or act, leave it off. MCP adds context and surface area. A short list is often better engineering than a large one.