MCP

Model Context Protocol (MCP) Cheat Sheet

Primitives, transports and the client-server handshake

MCP standardises how an AI application connects to external context and tools, so one server works with every compatible client.

Advanced 1 min read 14 Entries Version 1.0 Sabir Updated 2
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Server primitives

Primitive Is Controlled by
Tools Actions the model may invoke The model, at its discretion
Resources Readable context — files, records, pages The application, which chooses what to attach
Prompts Reusable templates the user can trigger The user, usually from a menu

Transports

Transport Runs Use for
stdio As a local subprocess Local tools, filesystem access, developer machines
Streamable HTTP As a remote service Shared and hosted servers
SSE Remote, server-sent events Legacy deployments; superseded by streamable HTTP

Handshake

Message Direction
initialize client → server: protocol version and capabilities
initialize result server → client: its own capabilities
notifications/initialized client → server: ready
tools/list client → server: discover available tools
tools/call client → server: invoke one
resources/list, resources/read client → server: discover and fetch context
prompts/list, prompts/get client → server: discover and expand templates

An MCP server is a trust boundary

Installing an MCP server grants it whatever access it asks for, and its tool descriptions become part of the model's instructions. Treat a third-party server the way you would treat a browser extension: read what it does, prefer least privilege, and remember that content it returns can itself contain injected instructions.

Code examples

Registering a local stdio server

The client config that starts a server as a subprocess and speaks JSON-RPC over stdin/stdout.

JSON mcp-config.json Download 
{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "/srv/data"],
      "env": { "LOG_LEVEL": "info" }
    },
    "internal-api": {
      "type": "http",
      "url": "https://tools.internal.example/mcp",
      "headers": { "Authorization": "Bearer ${API_TOKEN}" }
    }
  }
}

Frequently asked questions

How is MCP different from plain function calling?
Function calling is per-application: you define tools inside your own code. MCP is a protocol, so one server works with every compatible client, and it adds resources and prompts alongside tools.
Is installing an MCP server safe?
Treat it like a browser extension. It runs with the access you grant it, and its tool descriptions become part of the model instructions. Prefer least privilege and read what it does first.

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