Overview

Protocol Revision: draft

Servers provide the fundamental building blocks for adding context to language models via MCP. These primitives enable rich interactions between clients, servers, and language models:

• Prompts: Pre-defined templates or instructions that guide language model interactions
• Resources: Structured data or content that provides additional context to the model
• Skills: Structured instructions and workflows that help models perform tasks
• Tools: Executable functions that allow models to perform actions or retrieve information

Each primitive can be summarized in the following control hierarchy:

Primitive	Control	Description	Example
Prompts	User-controlled	Interactive templates invoked by user choice	Slash commands, menu options
Resources	Application-controlled	Contextual data attached and managed by the client	File contents, git history
Skills	Model-controlled	Structured instructions loaded on demand	Domain expertise, workflows
Tools	Model-controlled	Functions exposed to the LLM to take actions	API POST requests, file writing

Explore these key primitives in more detail below:

Prompts

Resources

Skills

Tools