JSON Glossary

A plain-text data format used by APIs, tools, agents, and configuration files to pass structured information around.

JSON — JavaScript Object Notation — is a text-based, language-independent format for exchanging structured data. Its values may be objects, arrays, strings, numbers, true, false, or null; object member names are strings.

It matters in agentic AI because tools need a shared way to pass information around. When an agent calls a tool, reads a configuration file, sends an API request, stores heartbeat state, or receives a structured result, JSON is often the little envelope carrying the meaning. It is not glamorous, but it is everywhere.

The useful intuition is this: ordinary prose is for humans; JSON is for machinery that needs to know exactly which value belongs to which name. A misplaced comma can break the machine. A well-shaped JSON object can make a tool call precise, auditable, and repeatable.

See also

• Tool
• MCP
• System Prompt

Source: IETF RFC 8259, “The JavaScript Object Notation (JSON) Data Interchange Format”.

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