MCP Server Capabilities: Core Building Blocks for AI Actions
Answer-first: Capabilities define exactly what actions an AI can request and under what conditions.
A capability is a single, clearly defined operation. This prevents accidental overreach and keeps system behavior predictable. By constraining what an AI can do, capabilities turn abstract reasoning into tangible, safe operations.
| Capability | Input | Output | Side Effect |
|---|---|---|---|
| Get customer overview | Customer ID | Summary object | None |
| Create support ticket | Ticket details | Confirmation | Ticket added |
| Schedule meeting | Attendees, time | Confirmation | Calendar updated |
The AI cannot invent new actions; it can only select from defined capabilities. This creates clarity for developers, operators, and auditors and ensures predictable behavior across AI updates. In practice, this transforms AI from a “black box” into a system whose actions you can anticipate and trust.