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MCP drills

Everything MCP speaks is JSON — so learn it by writing it. Wire servers into a host's mcpServers config, define the server primitives (tools, resources, prompts), and hand-write the JSON-RPC messages (initialize, capabilities, tools/call). Every drill is graded live in your browser against the real shapes — no AI, no autocomplete.

Why this matters:MCP is becoming the default way agents connect to tools and data. Reading about it isn't the same as being able to write a correct tool definition or an initialize handshake from memory. These drills make the shapes muscle memory. Authored against spec revision 2025-11-25.

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Client configuration

0/3 done

Wire MCP servers into a host with an `mcpServers` config — local stdio servers (command / args / env) and remote Streamable-HTTP servers (type / url). The JSON a host like Claude Desktop reads on startup.

1. Add a local (stdio) serverAdd a local stdio MCP server to the `mcpServers` object. Name it "filesystem":easy 2. Pass a secret via envThe "github" stdio server needs an API token. Add an `env` map to it that sets "GITHUB_TOKEN". (A stdio server gets its secrets from environment variables — never over the protocol.)medium 3. Add a remote (Streamable HTTP) serverAdd a REMOTE server named "weather" that connects over Streamable HTTP instead of a subprocess:medium

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Server primitives

0/5 done

Define what a server exposes: TOOLS (name + inputSchema + optional outputSchema/annotations), RESOURCES (uri + mimeType), and PROMPTS (arguments). The exact JSON shapes a client discovers and uses.

1. Define a toolDefine an MCP tool named "get_weather":medium 2. Add a structured outputSchemaThis tool already has an inputSchema. Add an `outputSchema` so its result is machine-usable:hard 3. Annotate a read-only toolAdd `annotations` to the "list_files" tool declaring it read-only and non-destructive:medium 4. Define a resourceDefine an MCP resource for an app config file:easy 5. Define a prompt with argumentsDefine an MCP prompt named "summarize" that takes one required argument:medium

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Protocol messages

0/3 done

Speak the wire protocol: the JSON-RPC `initialize` handshake, capability declarations, and a `tools/call` request. The messages that actually flow between client and server.

1. Write the initialize requestWrite the JSON-RPC `initialize` request a client sends first:medium 2. Declare server capabilitiesIn the server's initialize RESPONSE, declare its `capabilities`:medium 3. Write a tools/call requestWrite the JSON-RPC request that invokes the "get_weather" tool:medium