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

# Structured outputs

> Structured Outputs vs JSON mode: how Agno enforces output_schema and when to fall back to use_json_mode.

Agno agents support two methods for schema-compliant responses: **Structured Outputs** and **JSON mode**. Both use the agent's `output_schema` parameter.

## Structured Outputs (Default if supported)

If the model class supports it, Agno agents use Structured Outputs by default. The schema (Pydantic or JSON Schema) is passed to the model provider's API. For successfully completed, non-refusal responses, providers that support strict Structured Outputs validate the response against that schema. Handle refusals, incomplete generations, and provider errors separately.

```python theme={null}
from pydantic import BaseModel
from agno.agent import Agent
from agno.models.openai import OpenAIChat

class User(BaseModel):
    name: str
    age: int
    email: str

agent = Agent(
    model=OpenAIChat(id="gpt-5.4-mini"),
    description="You are a helpful assistant that can extract information from a user's profile.",
    output_schema=User,
)
```

The agent returns a `User` object instead of free-form text. Structured Outputs are a good fit for tasks where the output shape has to be right, like entity extraction or generating content for UI rendering.

## JSON Mode

Some model classes do not support Structured Outputs, and sometimes you want to bypass it even when they do. Set `use_json_mode=True` to enable JSON mode.

```python theme={null}
from pydantic import BaseModel
from agno.agent import Agent
from agno.models.openai import OpenAIChat

class User(BaseModel):
    name: str
    age: int
    email: str

agent = Agent(
    model=OpenAIChat(id="gpt-5.4-mini"),
    description="You are a helpful assistant that can extract information from a user's profile.",
    output_schema=User,
    use_json_mode=True,
)
```

JSON mode injects a description of the expected JSON structure into the system prompt and instructs the model to return valid JSON. The response is not validated against the schema at the API level.

## When to Use Which

| Situation                                             | Mode                                      |
| ----------------------------------------------------- | ----------------------------------------- |
| Model supports Structured Outputs                     | Structured Outputs (default)              |
| Model lacks Structured Outputs support                | JSON mode (Agno falls back automatically) |
| Model can't combine tools with Structured Outputs     | JSON mode                                 |
| Broad compatibility matters and you validate manually | JSON mode                                 |

## Next Steps

* [Structured output for agents](/input-output/structured-output/agent)
* [Model compatibility](/models/compatibility)