MCP (Model Context Protocol)
ToolDefinition
An open standard by Anthropic for connecting AI assistants to external data sources and tools. Defines a common interface so any MCP-compatible client (Claude, Cursor, etc.) can plug into any MCP-compatible server (databases, APIs, filesystems).
Related Terms
Tool Use
The ability of an LLM to invoke external tools — web search, code execution, calculators, APIs — during inference. The model decides when and how to call tools, receives the result, and incorporates it into its response.
Function Calling
A structured capability where the model outputs a JSON object describing which function to call and with what arguments, rather than plain text. The calling application executes the function and feeds the result back. Standard in GPT-4, Claude, and Gemini.
Agent
An AI system that can autonomously plan and execute multi-step tasks by calling tools, browsing the web, writing code, and interacting with external services — all without continuous human intervention.