technical-term · Multi-agent & protocols · maturing · Reviewed
Model Context Protocol
An open protocol for connecting AI applications to servers that expose context, tools, prompts, and related capabilities.
Definition
Model Context Protocol standardizes how a host application creates clients, negotiates capabilities, and exchanges messages with servers that expose resources and actions. MCP improves interoperability; it does not determine whether a capability is trustworthy, whether a caller has business standing, or whether a proposed effect should be allowed.
The protocol has broad adoption and continues to evolve, including enterprise authorization profiles and versioned extensions.
Why it matters
MCP separates an AI application from many capability implementations through shared contracts.
Security still requires server trust, identity, authorization, input validation, output handling, network boundaries, and evidence.
System anatomy
- Host
- The application that coordinates user intent, permissions, and one or more clients.
- Client
- A protocol connection maintained by the host for a server.
- Server
- A process or service exposing declared resources, tools, prompts, or capabilities.
- Transport & messages
- The negotiated communication and request-response layer.
Important distinctions
- Tool calling
- Tool calling is a model interaction pattern; MCP is one protocol for capability discovery and exchange.
- Control plane
- MCP transports capability requests; it does not grant authority or replace policy enforcement.
Implementation signals
- Pin and govern protocol versions
- Authenticate every principal and authorize every effect
- Treat server descriptions and results as untrusted input
- Register server ownership, purpose, data access, and incident path
Failure modes
- Protocol compatibility is mistaken for trust
- A server expands capability after approval without recertification
- Tool output injects new instructions into the agent
Sources and further study
- Model Context Protocol — Model Context Protocol architecture overview
Documents the host, client, server, capability-negotiation, and message layers used to connect AI applications with context and tools.
Use in this library: Standard or protocol. Protocol connectivity and capability discovery do not confer business authority, validate tool output, or make a server trustworthy.
protocol · protocol · Published 2026-07-28 - Model Context Protocol — Enterprise-Managed Authorization for MCP
An emerging authorization pattern for enterprise-managed agent access to MCP servers.
Use in this library: Standard or protocol. A specification defines an interface or control pattern; conformance alone does not establish authorization, security, or fitness for a use case.
protocol · protocol · Published 2026-06-18 - Model Context Protocol — Model Context Protocol 2026-07-28 release candidate
A current protocol release candidate illustrating that agent-tool interoperability, authorization, and extension surfaces continue to evolve and require explicit version governance.
Use in this library: Standard or protocol. A specification defines an interface or control pattern; conformance alone does not establish authorization, security, or fitness for a use case.
protocol · protocol · Published 2026-07-28 - OWASP GenAI Security Project — OWASP Top 10 for Agentic Applications 2026
A threat-oriented reference for goal hijacking, tool misuse, identity abuse, memory poisoning, and cascading agent failures.
Use in this library: Official guidance. Guidance describes recommended practice; citation does not prove that a control is implemented or effective in a particular environment.
guidance · guidance · Published 2025-12