Glossary · AI and language-model infrastructure
MCP tool
An executable function an MCP server advertises for the client to request with defined inputs and outputs.
Definition
An MCP tool represents an action such as requesting an API report, searching an approved index, validating a file, or creating a controlled record. The tool definition describes its name, purpose, and input schema; the server implements the action and returns structured content.
Why it matters
Explicit tool contracts make actions more inspectable than vague “AI can access everything” claims.
Common misunderstanding
A listed tool is a capability, not blanket authorization to call it in every context. Consequential calls may still require human approval.
Related terms
Related system family: Operations & Automation
Sources
- Model Context Protocol architecture overview (opens in a new tab) · Model Context Protocol
Last reviewed July 16, 2026