AI agent glossary
JSON Schema
A standard format for describing the shape of JSON data, used to define tool inputs and structured outputs for language models.
JSON Schema lets you describe what valid data looks like: which fields exist, what type each one is, which are required, and what values are allowed. Software can then check whether a given piece of JSON matches.
In agent work, JSON Schema shows up everywhere. When you define a tool for a model, you describe its parameters with a schema, and the model uses that description to construct valid calls. When you request structured output, a schema tells the model exactly what shape its reply must take.
The descriptions inside a schema matter as much as the types. A clear description of each field is effectively part of your prompt, and it often decides whether the model fills the field correctly.
A get_weather tool might declare an object with a required string field city and an optional field units that must be either celsius or fahrenheit.
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