> ## Documentation Index
> Fetch the complete documentation index at: https://docs.agenticenv.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# JSON Response

> Configure ResponseFormat with a JSONSchema to get structured machine-parseable output from the agent

Constrains every LLM call to a JSON schema using `WithResponseFormat` — the model returns parseable structured data, not free-form markdown.

Source: [`examples/agent_with_json_response/`](https://github.com/agenticenv/agent-sdk-go/tree/main/examples/agent_with_json_response)

## What it demonstrates

* `interfaces.ResponseFormat` with `ResponseFormatJSON` and `JSONSchema`
* Parsing `result.Content` as JSON after `Run`
* Schema enforcement across tool rounds

## Run

From `examples/`:

```bash theme={null}
go run ./agent_with_json_response "What is the capital of France?"
```

## Key code

Define the schema once at agent construction:

```go theme={null}
rf := &interfaces.ResponseFormat{
    Type: interfaces.ResponseFormatJSON,
    Name: "FactAnswer",
    Schema: interfaces.JSONSchema{
        "type": "object",
        "properties": interfaces.JSONSchema{
            "answer":       interfaces.JSONSchema{"type": "string"},
            "confidence":   interfaces.JSONSchema{"type": "string", "enum": []any{"low", "medium", "high"}},
        },
        "required":             []any{"answer", "confidence"},
        "additionalProperties": false,
    },
}

a, err := agent.NewAgent(
    agent.WithLLMClient(llmClient),
    agent.WithResponseFormat(rf),
)
```

See [Response format](/features/response-format) for provider support and limitations.

## Expected output

```json theme={null}
{"answer":"Paris","confidence":"high"}
```

The model is constrained to return valid JSON matching the schema — `result.Content` is always parseable with `json.Unmarshal`.

## Learn more

<CardGroup cols={2}>
  <Card title="Response Format" icon="code" href="/features/response-format">
    Schema design and parsing
  </Card>

  <Card title="Token Usage" icon="coins" href="/features/token-usage">
    Usage on structured runs
  </Card>
</CardGroup>