fiddler-adk

Fiddler SDK for instrumenting Google ADK (Agent Development Kit) with OpenTelemetry.

This package lives in the fiddler-sdk monorepo under packages/integrations/fiddler-adk/. It depends on fiddler-otel for the OTel pipeline, span attributes, and span processing.

Install

pip install fiddler-adk

Usage

from fiddler_otel import FiddlerClient
from fiddler_adk import GoogleADKInstrumentor

client = FiddlerClient(
    api_key='YOUR_API_KEY',
    application_id='YOUR_APPLICATION_ID',  # UUID4 from the Fiddler GenAI Applications page
    url='https://your-instance.fiddler.ai',
)
GoogleADKInstrumentor(client).instrument()

# Build and run ADK agents as usual — traces flow to Fiddler automatically.

How it works

Google ADK emits OpenTelemetry spans natively (invoke_agent, call_llm, execute_tool, ...) through a tracer that resolves against the global tracer provider. GoogleADKInstrumentor.instrument():

1. Sets up an isolated Fiddler tracing pipeline. Uses FiddlerClient to initialise a dedicated tracer, provider, processor, and OTLP exporter. The client's provider is promoted to global so ADK's gcp.vertex.agent tracer resolves to it. The SDK operates in standalone mode — it does not interact with customer-configured tracers or providers.
2. Propagates session identity. ADK sets gen_ai.conversation.id on child spans (invoke_agent, call_llm, etc.) but not on the parent invocation root span. The ADKSpanProcessor backfills it to the root so the Fiddler UI can group all spans in a turn under the same session.

Span-type classification, content extraction (LLM input/output, tool I/O, system instructions), and attribute normalization are handled by the Fiddler backend — the SDK does not parse or transform ADK's content attributes.

Supported versions

• google-adk >= 1.34.2
• opentelemetry-api >= 1.37.0
• Python 3.10+

Content capture

ADK includes full LLM request/response payloads in span attributes by default. Set ADK_CAPTURE_MESSAGE_CONTENT_IN_SPANS=false to disable ADK's payload capture if your prompts may contain PII.

See examples/ in this directory for a runnable agent.