Advanced35 Minutes
Model Context Protocol (MCP) Architecture
Model Context Protocol (MCP) is an open standard that decouples AI models from proprietary tool integrations, enabling secure, modular connections between LLM applications and data sources.
Prerequisites
intro-agentic-archJSON-RPC / SSE
Learning Objectives
- •Understand the MCP Client-Server protocol model created by Anthropic.
- •Differentiate MCP Resources, Prompts, and Tools.
- •Build a production MCP tool server with secure sandbox execution.
In-Depth Architecture & Mechanics
Why Model Context Protocol (MCP)? Before MCP, every AI agent framework (LangChain, CrewAI, custom code) implemented proprietary connectors. If you built a connector for PostgreSQL, you had to rewrite it for every framework.
MCP creates a standard client-host-server architecture: - **Host**: The user-facing application (e.g. IDE, Agent runtime). - **Client**: Connects 1:1 with an MCP Server. - **Server**: Exposes three core capabilities: 1. **Resources**: Passive data read-only streams (like file contents, database logs). 2. **Prompts**: Standardized templates that guide users or models. 3. **Tools**: Executable functions that make changes or perform computations with JSON Schema validation.
System Architecture Flow:
[ Host Application ]
│
[ MCP Client ]
│ (JSON-RPC over Stdio / SSE)
▼
[ MCP Server ] ──> [ Database / Internal APIs / Shell ]Worked code example:
MCP Server Tool Definition (Python FastMCP)
python
from mcp.server.fastmcp import FastMCP
mcp = FastMCP("Database-Inspector")
@mcp.tool()
def explain_query_plan(query: str) -> str:
"""Explains PostgreSQL query execution plan and flags table scans."""
# Production: execute EXPLAIN (ANALYZE, BUFFERS) with read-only credentials
return f"Execution plan analyzed for: {query}"
Architectural Tradeoffs
Standardization vs Custom Protocol: Standard JSON-RPC overhead is slightly higher than raw in-memory calls, but unlocks universal cross-platform tool reuse.
Transport choices: Stdio is zero-network local, while SSE (Server-Sent Events) is required for distributed microservices.
Common Anti-Patterns
Granting unrestricted write permissions without confirmation schemas in MCP tools.
Exposing raw SQL execution without strict read-only replica separation.
Staff & Principal Interview Questions
Confidence: