Model Context Protocol
Anthropic's open standard for agent-to-tool communication—a universal connector that enables any compliant agent to interact with any compliant tool.
The Model Context Protocol addresses a fundamental challenge in agent development: how to reliably connect AI models to external capabilities without vendor-specific integrations. MCP provides a universal connector that standardizes tool invocation across the ecosystem.
"MCP provides a universal, standardized, plug-and-play connector that lets any LLM securely integrate with any external tool, API, or dataset."
Core Architecture
MCP implements a client-server architecture where the agent runtime hosts an MCP client that communicates with external MCP servers. Each server exposes one or more tools—well-defined functions with explicit input schemas and output types.
MCP Primitives
MCP defines four core primitives that enable rich agent-tool interactions:
9-Step MCP Workflow
The complete MCP interaction follows a well-defined sequence from initialization through result delivery:
Initialization
MCP Client sends initialize request with protocol version and client capabilities
Capability Exchange
MCP Server responds with its capabilities: available tools, resources, prompts, and sampling support
User Query
User submits a natural language query or request to the agent
LLM Reasoning
LLM analyzes the query and determines which MCP tool(s) to invoke
Tool Invocation
MCP Client sends tool call request with structured arguments to MCP Server
External Execution
MCP Server executes the tool, potentially calling external APIs or databases
Result Return
MCP Server returns structured result to MCP Client
Response Synthesis
MCP Client delivers the final processed result to the user
Async Notifications
MCP Server can push notifications or updates back to the MCP Client at any time
MCP Registry
An MCP Registry is a centralized, machine-readable directory that lists MCP servers, their capabilities, connection details, and metadata. This enables clients and IDEs to easily discover and install servers without manual configuration.
Security Model
🔑 Protocol Authorization
Aligns with OAuth 2.1 concepts including Auth Server Metadata, Dynamic Client Registration, and Resource Metadata. Enables scoped access tokens for restricted MCP servers.
📋 Version Negotiation
Messages include explicit protocolVersion fields, ensuring clients and servers only operate when versions are compatible—limiting downgrade or mismatch risks.
✅ Consent & Tool Gating
User consent and explicit authorization are part of the protocol's intended flow, standardizing a "consent checkpoint" in the lifecycle of tool calls.
Implementation Example
MCP ensures that any compliant agent can call any compliant tool—preventing vendor lock-in while maintaining consistent security and audit capabilities across the enterprise.