# Protocol Features

This page covers cross-cutting MCP protocol features.

## MCP Primitives

The MCP protocol defines three core primitives that servers can implement:

| Primitive | Control               | Description                                         | Example Use                  |
|-----------|-----------------------|-----------------------------------------------------|------------------------------|
| Prompts   | User-controlled       | Interactive templates invoked by user choice        | Slash commands, menu options |
| Resources | Application-controlled| Contextual data managed by the client application   | File contents, API responses |
| Tools     | Model-controlled      | Functions exposed to the LLM to take actions        | API calls, data updates      |

## Server Capabilities

MCP servers declare capabilities during initialization:

| Capability   | Feature Flag                 | Description                        |
|--------------|------------------------------|------------------------------------|
| `prompts`    | `listChanged`                | Prompt template management         |
| `resources`  | `subscribe`<br/>`listChanged`| Resource exposure and updates      |
| `tools`      | `listChanged`                | Tool discovery and execution       |
| `logging`    | -                            | Server logging configuration       |
| `completions`| -                            | Argument completion suggestions    |

## Pagination

For pagination details, see:

- Server-side implementation: [Building Servers - Pagination](server.md#pagination-advanced)
- Client-side consumption: [Building Servers - Client-side Consumption](server.md#client-side-consumption)