C1
Tools, Skills, Plugins, and Extensions
Use precise names for executable operations, reusable capabilities, installable packages, and negotiated protocol features.
- 01Distinguish a tool from a reusable skill
- 02Explain why plugin and extension are ecosystem-specific packaging terms
- 03Choose a capability boundary that can be tested and permissioned
Four different layers
vocabulary| Term | Plain-English meaning |
|---|---|
| Tool | One typed operation, such as lookup_order |
| Skill | A reusable capability that may combine instructions, tools, examples, or a specialist workflow |
| Plugin | An installable package for a particular host product |
| Extension | An optional protocol feature that both peers agree to use |
Example: refund investigation
A tool retrieves one order. A skill investigates a refund by using order lookup, payment history, policy instructions, and a report template. A host-specific plugin installs that capability into an application. An MCP extension may add an optional protocol behavior such as durable tasks.
Common MisconceptionAn MCP server is a plugin.
CorrectionAn MCP server speaks a protocol. A plugin may install or configure one, but the concepts are not interchangeable.
Deep dive: Capability packaging
Keep a skill small enough to test as one promise. Document its inputs, outputs, tools, permissions, stopping conditions, and known failure modes. If two parts need different trust or release cycles, split them.
References & deeper reading (2)
- Tool Use OverviewAnthropic
- MCP Extensions OverviewModel Context Protocol
Retrieval Practice
Check one idea at a time
Match each term to the best description.
Match each item to its pair.