Summary
The smallest thing to point a client at when you need to know whether the fault is yours or the server's.
Three tools, no credentials and no upstream service means anything that goes wrong is in your transport, your config or your client — nothing else is in the path to blame. Outside that diagnostic role it does nothing you would want: the answers are a greeting, a sum and a tool list.
What it is
A minimal reference server with three tools — echo, add and debug — whose only job is to answer, so a client's transport and tool-calling path can be exercised on its own.
What you get
- echo returns the message you sent with a Hello prefix, which is a completed round trip you can read
- add takes two numbers and returns the sum, exercising typed arguments rather than a string passthrough
- debug lists the tools and methods the server exposes, which is the shape your client should be rendering from a tool listing
Requirements
Nothing at all: no account, no key, and no service sitting behind it.
Setup effort
One command — npx mcp-hello-world