MCP Server Builder

An MCP server is how Claude reaches a system it does not otherwise know about — your database, your internal API, your ops tooling. The protocol is small. Almost every real problem is a design problem: which tools to expose and what they return.

Decide the Shape First

Local (stdio) — runs on the user's machine, launched by the client, credentials from the local environment. Right for developer tooling and anything touching localhost or a local database. Only that machine gets it.

Remote (HTTP) — deployed once, reached by URL, OAuth for identity. Right when a team needs it, or when the data lives in a service rather than on a laptop. Everyone gets updates the moment you deploy.

Build remote when more than one person will use it. Retrofitting local-only to multi-user later means redoing auth from scratch.

Tool Design — the part that matters

Tools are an interface for a model, not a REST API. The common failure is exposing twenty thin endpoint wrappers and watching the model chain them badly.