Hosts, clients and servers
See which component selects a tool, sends the request, checks permissions and returns the result.
Compare MCP hosts, clients, and serversIndependent Model Context Protocol research
Model Context
Protocol
How MCP connects AI applications to tools and data, with guides to building servers, choosing transports, and handling permissions.
Protocol statusCurrent
202607.28
Requests carry their own context. Servers advertise operations through discovery, and Tasks is available as an extension.
Read the annotated change guideArchitecture decisions
Hosts, servers and capabilities
A host runs the AI application. Its MCP client connects to servers that provide tools, data and prompts.
Local and remote servers
Local servers run on your machine; remote servers are reached over a network. Compare file access, credentials and maintenance.
Choose local or remote MCPTools, resources and prompts
Tools perform operations, resources supply data, and prompts prepare messages. Examples show when to combine them.
Compare tools, resources, and promptsFor existing servers, check protocol versions or review MCP security. For an introduction, read the plain-language MCP overview.
01
July 2026 revision
MCP 2026-07-28 changed how clients discover and call servers.
Before July 2026, an MCP connection began with initialization and capability negotiation. The current core is stateless: requests carry their own context, servers advertise operations through discovery, and formerly core features can live as extensions.
Older clients may still use initialization and sessions. The version comparison explains which message flows changed and what a migration needs to account for.
MCP guides
Definitions, code examples, protocol changes and security controls.
Beginner guideSpec 2026-07-28
What Is an MCP Server? A Beginner’s Guide to the Model Context Protocol
Learn what an MCP server is, how hosts, clients, tools, resources and transports work, and how local and remote MCP differ in the current protocol.
Architecture cornerstoneSpec 2026-07-28
MCP Host vs Client vs Server: Differences and Examples
Compare MCP hosts, clients and servers in one diagram. See who coordinates the model, sends requests, executes tools and controls permissions.
ArchitectureSpec 2026-07-28
What Is an MCP Gateway? Architecture, Security, and When to Use One
Learn how MCP gateways route and govern tools, how MCP 2026-07-28 changes gateway design, and when a gateway adds value—or needless complexity.
Architecture decisionSpec 2026-07-28
MCP Gateway vs API Gateway: Differences, Overlap, and When You Need Both
Compare API gateways and MCP gateways, identify the controls each owns, and choose the smallest architecture that safely supports your MCP servers.
Deployment decisionSpec 2026-07-28
Local vs Remote MCP Servers: Which Should You Use?
Choose between local and remote MCP servers. Compare machine access, stdio, HTTP, security, credentials and maintenance, with a practical decision table.
Primitive comparisonSpec 2026-07-28
MCP Tools vs Resources vs Prompts: When to Use Each
Tools perform operations, resources expose addressable data, and prompts provide reusable messages. Compare the three MCP primitives with practical examples.
Interactive MCP UISpec Apps 2026-01-26 · MCP 2026-07-28
MCP Apps Explained: Architecture, Client Support and Security
Understand MCP Apps with architecture diagrams, a client support table, security boundaries and fallback guidance. Includes dated sources and data downloads.
MCP extensionsSpec 2026-07-28
Skills over MCP: How to Serve and Check Skill Files
Serve SKILL.md files through MCP, check which clients support the extension, and use Inspector to detect a file that no longer matches its manifest.
Version compatibilitySpec 2026-07-28
MCP Protocol Versions: Compatibility, Changes and Migration
Compare MCP protocol versions side by side. Use the compatibility matrix, breaking-change guide and migration checklist to plan a client or server update.
Architecture comparisonSpec 2026-07-28
MCP vs Function Calling: Architecture, Differences, and When to Use Each
Compare MCP with native function calling and tool use. Learn how they work together, where APIs fit, their security and latency trade-offs, and when to use each.
Agent protocol comparisonSpec 2026-07-28
MCP vs A2A: Differences, Architecture, and When to Use Each Protocol
Compare MCP and A2A for AI agents. Learn how tools differ from skills, how Tasks and discovery differ, how the protocols work together, and when to use either or both.
Current specificationSpec 2026-07-28
MCP 2026-07-28: What Changed and How to Migrate
A practical guide to MCP's stateless 2026 specification, including per-request metadata, version discovery, multi-round trips, subscriptions, extensions, and legacy compatibility.
Start hereSpec 2026-07-28
What Is the Model Context Protocol? A Practical 2026 Guide
A version-aware explanation of MCP: the problem it solves, its architecture and capabilities, and how the stateless 2026 core differs from legacy MCP.
Architecture guideSpec 2026-07-28
How MCP Works: Hosts, Clients, Servers, and Every Request
A version-aware explanation of MCP architecture, primitives, message patterns, transports, and trust boundaries under the 2026-07-28 specification.
Migration guideSpec 2026-07-28
MCP Stateful-to-Stateless Migration: The 2026 Protocol
A practical migration guide from MCP's initialize-and-session era to the stateless 2026-07-28 protocol, with compatibility and state-design patterns.
Security field guideSpec 2026-07-28
MCP Security: Threats, Vulnerabilities, and How to Secure MCP Servers
A technical guide to MCP security covering OAuth, prompt injection, tool poisoning, malicious servers, CVEs, supply-chain risks, and secure local and remote deployment.
Transport guideSpec 2026-07-28
MCP Transports: stdio, Streamable HTTP, and Legacy SSE
Compare stdio, Streamable HTTP, and legacy SSE. Match stdio-to-HTTP and SSE proxy directions to the client, server, and protocol versions you need.
Protocol timelineSpec 2026-07-28
The History of MCP: From Early Commits to an Open Standard
A primary-source timeline of MCP, from its pre-launch repository and November 2024 announcement through adoption, open governance, and the stateless 2026 core.
ComparisonSpec 2026-07-28
MCP vs API: Differences and When to Use Each
Compare MCP with REST and other APIs through one customer lookup: what the adapter adds, which permissions remain, and when a direct API is enough.
Tested Python guideSpec 2026-07-28
Build an MCP Server in Python
Build a local MCP server with Python, expose one typed tool, verify its schema and errors, and call it through an actual stdio subprocess.
Schema referenceSpec 2026-07-28
MCP Tool Schema: Inputs, Structured Output, and Errors
Learn how MCP tool input and output schemas work, how errors differ from successful results, and how to test the contract a server actually advertises.
History
From first public commit to stateless core
Specification and SDK history begin before the public launch.
A stateful, JSON-RPC-based protocol with tools, resources, prompts, and more.
Streamable HTTP and a protocol authorization framework arrive.
MCP joins the Agentic AI Foundation under the Linux Foundation.
Stateless core, discovery, MRTR, extensions, and explicit deprecations.
References
MCP source library
Search 551 records covering specifications, SDKs, repository history, security advisories and research.