Model Context Protocol FAQ

What is MCP?

The Model Context Protocol (MCP) is an open protocol that enables secure, controlled interactions between AI applications and local or remote resources. It provides a standardized way to connect LLMs with the context they need.

Core Architecture

MCP follows a client-server architecture where:

  • Hosts are LLM applications (like Claude Desktop or IDEs) that initiate connections
  • Clients maintain 1:1 connections with servers, inside the host application
  • Servers provide context, tools, and prompts to clients

Protocol Layer

The protocol layer handles:

  • Message framing
  • Request/response linking
  • High-level communication patterns

Transport Layer

MCP supports multiple transport mechanisms:

Stdio Transport

  • Uses standard input/output for communication
  • Ideal for local processes

HTTP with SSE Transport

  • Uses Server-Sent Events for server-to-client messages
  • HTTP POST for client-to-server messages

All transports use JSON-RPC 2.0 to exchange messages.

Message Types

MCP has these main types of messages:

  1. Requests expect a response from the other side
  2. Notifications are one-way messages that don't expect a response
  3. Results are successful responses to requests
  4. Errors indicate that a request failed

Connection Lifecycle

1. Initialization

  • Client sends initialize request with protocol version and capabilities
  • Server responds with its protocol version and capabilities
  • Client sends initialized notification as acknowledgment
  • Normal message exchange begins

2. Message Exchange

After initialization, the following patterns are supported:

  • Request-Response: Client or server sends requests, the other responds
  • Notifications: Either party sends one-way messages

3. Termination

Either party can terminate the connection:

  • Clean shutdown via close()
  • Transport disconnection
  • Error conditions

Best Practices

Transport Selection

Local Communication

  • Use stdio transport for local processes
  • Efficient for same-machine communication
  • Simple process management

Remote Communication

  • Use SSE for scenarios requiring HTTP compatibility
  • Consider security implications including authentication and authorization

Message Handling

Request Processing

  • Validate inputs thoroughly
  • Use type-safe schemas
  • Handle errors gracefully
  • Implement timeouts

Progress Reporting

  • Use progress tokens for long operations
  • Report progress incrementally
  • Include total progress when known

Security Considerations

Transport Security

  • Use TLS for remote connections
  • Validate connection origins
  • Implement authentication when needed

Message Validation

  • Validate all incoming messages
  • Sanitize inputs
  • Check message size limits
  • Verify JSON-RPC format

Resource Protection

  • Implement access controls
  • Validate resource paths
  • Monitor resource usage
  • Rate limit requests

Getting Started

  1. Choose your implementation language (TypeScript, Python, Go, or Rust)
  2. Set up your development environment
  3. Implement the protocol handlers
  4. Add your custom functionality
  5. Test thoroughly
  6. Deploy and monitor

For more detailed information, visit the official documentation.