The Agent Glossary

Plain-English definitions for the AI-agent era — agentic commerce, the Model Context Protocol, GEO and agent payments. Every term answered in one sentence, then explained.

AI agents & concepts

AI agentRAG (Retrieval-Augmented Generation)Function calling (tool calling)A2A (Agent2Agent protocol)Prompt injection

Agentic commerce

Agentic commerceAgentic Commerce Protocol (ACP)Universal Commerce Protocol (UCP)AI shopping agentChatGPT Shopping

AI visibility (GEO/AEO)

Citation shareGenerative Engine Optimization (GEO)Answer Engine Optimization (AEO)llms.txtagents.mdAI OverviewsZero-click searchStructured data (schema markup)

Model Context Protocol

Model Context Protocol (MCP)MCP serverStreamable HTTP (MCP transport)MCP tool

Agent payments

x402AP2 (Agent Payments Protocol)Agentic payments

Ready to act on any of these?

Free tools for the agentic era.

Scan a store   Scan an MCP server