Chapter 150 · LLM Analytics Setup
Subchapter 150.26
references/openai-agents.mdMarkdown6 KBView on GitHub
Required
Setting up analytics starts with installing the PostHog Python SDK.
pip install posthog2
Required
Install the OpenAI Agents SDK. PostHog instruments your agent runs by registering a tracing processor. The PostHog SDK does not proxy your calls.
pip install openai-agentsProxy note
These SDKs do not proxy your calls. They only fire off an async call to PostHog in the background to send the data. You can also use LLM analytics with other SDKs or our API, but you will need to capture the data in the right format. See the schema in the manual capture section (opens in a new tab) for more details.
3
Required
Initialize PostHog with your project token and host from your project settings (opens in a new tab), then call instrument() to register PostHog tracing with the OpenAI Agents SDK. This automatically captures all agent traces, spans, and LLM generations.
from posthog import Posthog
from posthog.ai.openai_agents import instrument
posthog = Posthog(
"<ph_project_token>",
host="https://us.i.posthog.com"
)
instrument(
client=posthog,
distinct_id="user_123", # optional
privacy_mode=False, # optional
groups={"company": "company_id_in_your_db"}, # optional
properties={"conversation_id": "abc123"}, # optional
)Note: If you want to capture LLM events anonymously, don’t pass a distinct ID to
instrument(). See our docs on anonymous vs identified events (opens in a new tab) to learn more.
4
Required
Run your OpenAI agents as normal. PostHog automatically captures $ai_generation events for LLM calls and $ai_span events for agent execution, tool calls, and handoffs.
from agents import Agent, Runner
agent = Agent(
name="Assistant",
instructions="You are a helpful assistant.",
)
result = Runner.run_sync(agent, "Tell me a fun fact about hedgehogs")
print(result.final_output)You can expect captured $ai_generation events to have the following properties:
| Property | Description |
|---|---|
| $ai_model | The specific model, like gpt-5-mini or claude-4-sonnet |
| $ai_latency | The latency of the LLM call in seconds |
| $ai_time_to_first_token | Time to first token in seconds (streaming only) |
| $ai_tools | Tools and functions available to the LLM |
| $ai_input | List of messages sent to the LLM |
| $ai_input_tokens | The number of tokens in the input (often found in response.usage) |
| $ai_output_choices | List of response choices from the LLM |
| $ai_output_tokens | The number of tokens in the output (often found in response.usage) |
| $ai_total_cost_usd | The total cost in USD (input + output) |
| […] (opens in a new tab) | See full list (opens in a new tab) of properties |
5
Optional
PostHog captures the full trace hierarchy for complex agent workflows including handoffs and tool calls.
from agents import Agent, Runner, function_tool
@function_tool
def get_weather(city: str) -> str:
"""Get the weather for a city."""
return f"The weather in {city} is sunny, 72F"
weather_agent = Agent(
name="WeatherAgent",
instructions="You help with weather queries.",
tools=[get_weather]
)
triage_agent = Agent(
name="TriageAgent",
instructions="Route weather questions to the weather agent.",
handoffs=[weather_agent]
)
result = Runner.run_sync(triage_agent, "What's the weather in San Francisco?")This captures:
TriageAgent and WeatherAgentget_weather function callsRecommended
Confirm LLM events are being sent to PostHog
Let’s make sure LLM events are being captured and sent to PostHog. Under LLM analytics, you should see rows of data appear in the Traces and Generations tabs.


6
Recommended
Now that you’re capturing AI conversations, continue with the resources below to learn what else LLM Analytics enables within the PostHog platform.
| Resource | Description |
|---|---|
| Basics (opens in a new tab) | Learn the basics of how LLM calls become events in PostHog. |
| Generations (opens in a new tab) | Read about the $ai_generation event and its properties. |
| Traces (opens in a new tab) | Explore the trace hierarchy and how to use it to debug LLM calls. |
| Spans (opens in a new tab) | Review spans and their role in representing individual operations. |
| Anaylze LLM performance (opens in a new tab) | Learn how to create dashboards to analyze LLM performance. |
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