MCP vs Traditional APIs
How MCP differs from REST APIs and webhooks. Technical comparison for integration architects.
This article is part of our Comparison series.
Read the complete guide: What is MCP?REST APIs, Webhooks, GraphQL. These are the integration patterns we have built the web on. MCP is something different—an open protocol specifically designed for AI-to-tool communication. This article explains how MCP differs architecturally from traditional patterns, and why those differences matter for building AI agents.
Integration Patterns Overview
REST APIs
Stateless & Request-Based
The standard for web services. Client sends a request, server responds. Good for CRUD operations.
Webhooks
Event-Driven Push
Service calls you when something happens. Best for real-time updates and async workflows.
MCP
Session-Based Context
Persistent connection providing context and capabilities to an AI model.
MCP isn't replacing these patterns. Instead, it creates a standard way for AI models to consume these underlying APIs without custom glue code.
Architecture Comparison
The fundamental difference lies in the topology.
Your App (Client) ↓ HTTP Request API Server (Cloud) ↓ Database Query Database / Service
- • Communications happen over public internet (usually)
- • Authentication via headers (Bearer tokens)
- • Stateless (new connection per request)
Claude Desktop (Host) ↓ stdio / SSE MCP Server (Local Process) ↓ Direct API Call External Service (Gmail/Slack/etc)
- • Communications often local (stdio) or private network
- • Persistent connection (session-based)
- • AI-First: Exposes "Prompts", "Resources", and "Tools"
Key Technical Differences
REST: You read Swagger/OpenAPI docs to learn endpoints. You code the integration manually.
MCP: The protocol has built-in discovery. The client asks tools/list and the server replies with JSON schemas defining what it can do. The AI reads this schema dynamically.
REST: Returns raw data (JSON arrays). The client must know how to render or use it.
MCP: Can return "Resources" (files, logs, docs) meant for context window insertion. It's designed to feed an LLM, not just a UI.
REST: API keys travel over the wire. OAuth is handled by a redirect server.
MCP: Credentials stay on the local machine. The MCP server process holds the tokens and makes the calls. The host application (Claude) never sees the raw API keys.
When to Use Which?
For an integration architect, the choice depends on component boundaries.
- Building a web or mobile application UI.
- High-volume programmatic data sync.
- Service-to-service communication (microservices).
- You need strict, static type safety.
- Exposing capabilities to an LLM/AI Agent.
- You want "plug-and-play" tool access for Claude.
- Building local developer tools or CLI wrappers.
- Providing dynamic context (logs, active file) to an AI.
The Hybrid Future
The most powerful patterns combine both. Imagine a customer support system:
- RESTYour dashboard fetches ticket data via standard REST API to show tables and charts to humans.
- MCPYour AI assistant uses an MCP server to read specific ticket details and draft replies using the same underlying API context.
"MCP creates the 'Agent Interface' for your API, while REST remains the 'Application Interface'."