> ## 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.

# Langfuse Via OpenInference With Response Model

> Demonstrates Langfuse tracing for an Agno agent that returns structured output.

```python langfuse_via_openinference_response_model.py theme={null}
"""
Langfuse Via OpenInference With Response Model
==============================================

Demonstrates Langfuse tracing for an Agno agent that returns structured output.
"""

import base64
import os
from enum import Enum

from agno.agent import Agent
from agno.models.openai import OpenAIChat
from agno.tools.yfinance import YFinanceTools
from openinference.instrumentation.agno import AgnoInstrumentor
from opentelemetry.exporter.otlp.proto.http.trace_exporter import OTLPSpanExporter
from opentelemetry.sdk.trace import TracerProvider
from opentelemetry.sdk.trace.export import SimpleSpanProcessor
from pydantic import BaseModel, Field

# ---------------------------------------------------------------------------
# Setup
# ---------------------------------------------------------------------------
LANGFUSE_AUTH = base64.b64encode(
    f"{os.getenv('LANGFUSE_PUBLIC_KEY')}:{os.getenv('LANGFUSE_SECRET_KEY')}".encode()
).decode()
os.environ["OTEL_EXPORTER_OTLP_ENDPOINT"] = (
    "https://us.cloud.langfuse.com/api/public/otel"  # US data region
)
# os.environ["OTEL_EXPORTER_OTLP_ENDPOINT"] = "https://cloud.langfuse.com/api/public/otel"  # EU data region
# os.environ["OTEL_EXPORTER_OTLP_ENDPOINT"] = "http://localhost:3000/api/public/otel"  # Local deployment (>= v3.22.0)

os.environ["OTEL_EXPORTER_OTLP_HEADERS"] = f"Authorization=Basic {LANGFUSE_AUTH}"

tracer_provider = TracerProvider()
tracer_provider.add_span_processor(SimpleSpanProcessor(OTLPSpanExporter()))

# Start instrumenting agno
AgnoInstrumentor().instrument(tracer_provider=tracer_provider)


class MarketArea(Enum):
    USA = "USA"
    UK = "UK"
    EU = "EU"
    ASIA = "ASIA"


class StockPrice(BaseModel):
    price: str = Field(description="The price of the stock")
    symbol: str = Field(description="The symbol of the stock")
    date: str = Field(description="Current day")
    area: MarketArea


# ---------------------------------------------------------------------------
# Create Agent
# ---------------------------------------------------------------------------
agent = Agent(
    name="Stock Price Agent",
    model=OpenAIChat(id="gpt-5.2"),
    tools=[YFinanceTools()],
    instructions="You are a stock price agent. You check and return the current price of a stock.",
    debug_mode=True,
    output_schema=StockPrice,
)


# ---------------------------------------------------------------------------
# Run Example
# ---------------------------------------------------------------------------
if __name__ == "__main__":
    agent.print_response("What is the current price of Tesla?")
```

## Run the Example

<Steps>
  <Snippet file="create-venv-step.mdx" />

  <Step title="Install dependencies">
    ```bash theme={null}
    uv pip install -U agno openai openinference-instrumentation-agno opentelemetry-exporter-otlp opentelemetry-sdk yfinance
    ```
  </Step>

  <Step title="Export environment variables">
    <CodeGroup>
      ```bash Mac/Linux theme={null}
      export LANGFUSE_PUBLIC_KEY="your_langfuse_public_key_here"
      export LANGFUSE_SECRET_KEY="your_langfuse_secret_key_here"
      export OPENAI_API_KEY="your_openai_api_key_here"
      ```

      ```bash Windows theme={null}
      $Env:LANGFUSE_PUBLIC_KEY="your_langfuse_public_key_here"
      $Env:LANGFUSE_SECRET_KEY="your_langfuse_secret_key_here"
      $Env:OPENAI_API_KEY="your_openai_api_key_here"
      ```
    </CodeGroup>
  </Step>

  <Step title="Run the example">
    Save the code above as `langfuse_via_openinference_response_model.py`, then run:

    ```bash theme={null}
    python langfuse_via_openinference_response_model.py
    ```
  </Step>
</Steps>

Full source: [cookbook/observability/langfuse\_via\_openinference\_response\_model.py](https://github.com/agno-agi/agno/blob/main/cookbook/observability/langfuse_via_openinference_response_model.py)