Google Agents CLI Observability Agent Skill

ADK Observability Guide

> Cloud Trace works out of the box — no infrastructure needed. Prompt-response logging and BigQuery Agent Analytics require Terraform-provisioned infrastructure (service account, GCS bucket, BigQuery dataset). Run agents-cli infra single-project --project PROJECT_ID to provision these resources. See references/cloud-trace-and-logging.md for details, env vars, and verification commands. If your project isn't scaffolded yet, see /google-agents-cli-scaffold first.

Order of operations for agent_runtime deployments

For deployment_target = agent_runtime, run agents-cli infra single-project before the first agents-cli deploy. The Terraform module owns the entire Reasoning Engine resource (service account, deployment spec, env vars), so applying it after an SDK-based deploy creates a state mismatch Terraform can't reconcile without taking ownership of the whole resource.

Already ran agents-cli deploy? Two options:

• Switch to Terraform-managed — delete the SDK-deployed Reasoning Engine, then run agents-cli infra single-project and agents-cli deploy (sessions and in-flight state are lost).
• Keep the SDK-deployed instance — skip infra single-project and set the observability env vars by re-running agents-cli deploy --update-env-vars "KEY=VALUE,..."; deploy matches the existing Reasoning Engine by display name and updates it in place, preserving env vars set outside the deploy. You must also grant its service account the telemetry IAM roles the Terraform module would otherwise provision: roles/storage.admin (write completions to the logs bucket), roles/logging.logWriter, roles/cloudtrace.agent, plus roles/bigquery.dataOwner + roles/bigquery.jobUser when scaffolded with --bq-analytics. The full set lives in deployment/terraform/single-project/iam.tf (from app_sa_roles) and telemetry.tf. Terraform-managed env vars aren't available in this mode.

Reference Files

| File | Contents |

|------|----------|

| references/cloud-trace-and-logging.md | Scaffolded project details — Terraform-provisioned resources, environment variables, verification commands, enabling/disabling locally |

| references/bigquery-agent-analytics.md | BQ Agent Analytics plugin — enabling, key features, GCS offloading, tool provenance |

Observability Tiers

Choose the right level of observability based on your needs:

| Tier | What It Does | Scope | Default State | Best For |

|------|-------------|-------|---------------|----------|

| Cloud Trace | Distributed tracing — execution flow, latency, errors via OpenTelemetry spans | All templates, all environments | Always enabled | Debugging latency, understanding agent execution flow |

| Prompt-Response Logging | GenAI interactions exported to GCS, BigQuery, and Cloud Logging | ADK agents only | Disabled locally, enabled when deployed | Auditing LLM interactions, compliance |

| BigQuery Agent Analytics | Structured agent events (LLM calls, tool use, outcomes) to BigQuery | ADK agents with plugin enabled | Opt-in (--bq-analytics at scaffold time) | Conversational analytics, custom dashboards, LLM-as-judge evals |

| Third-Party Integrations | External observability platforms (AgentOps, Phoenix, MLflow, etc.) | Any ADK agent | Opt-in, per-provider setup | Team collaboration, specialized visualization, prompt management |

Ask the user which tier(s) they need — they can be combined. Cloud Trace is always on; the others are additive.

Cloud Trace

ADK uses OpenTelemetry to emit distributed traces. Every agent invocation produces spans that track the full execution flow.

Span Hierarchy

invoke_workflow (top-level run)
  └── invoke_agent (one per agent in the chain)
        ├── call_llm (model request)
        │     └── generate_content (underlying GenAI model call)
        └── execute_tool (tool execution)

Setup by Deployment Type

| Deployment | Setup |

|-----------|-------|

| Agent Runtime | Automatic — get_fast_api_app(otel_to_cloud=True), gated on GOOGLE_CLOUD_AGENT_ENGINE_ENABLE_TELEMETRY (set by deploy); exports to Cloud Trace/Logging + Agent Engine console |

| Cloud Run / GKE (scaffolded) | Automatic — get_fast_api_app(otel_to_cloud=True) exports to Cloud Trace/Logging |

| Cloud Run / GKE (manual) | Configure OpenTelemetry exporter in your app |

| Local dev | Works with agents-cli playground; traces visible in Cloud Console |

View traces: Cloud Console → Trace → Trace explorer

For detailed setup instructions (Agent Runtime CLI/SDK, Cloud Run, custom deployments), fetch https://adk.dev/integrations/cloud-trace/index.md.

Prompt-Response Logging

Captures GenAI interactions and exports to GCS (JSONL) and BigQuery (via log sinks + external tables). Content is governed by two independent tiers; the net Terraform-deploy default is full content in GCS/BigQuery, none in traces:

| Tier | Captures | Controlled by | Default (Terraform deploy) |

|------|----------|---------------|----------------------------|

| GCS/BigQuery completions | Full prompts/responses (the prompt-response logging feature) | OTEL_INSTRUMENTATION_GENAI_COMPLETION_HOOK=upload + LOGS_BUCKET_NAME | On — full content |

| Trace spans / Cloud Logging events | Span/event content | OTEL_INSTRUMENTATION_GENAI_CAPTURE_MESSAGE_CONTENT + ADK_CAPTURE_MESSAGE_CONTENT_IN_SPANS=false | Off — NO_CONTENT |

The tiers are independent: GCS/BigQuery uploads capture full content whenever their upload vars are set and do not honor OTEL_INSTRUMENTATION_GENAI_CAPTURE_MESSAGE_CONTENT, which governs the traces/events tier only. Its valid (experimental-semconv) values:

• NO_CONTENT — no content in spans/events (scaffolded default)
• EVENT_ONLY — content in Cloud Logging events
• SPAN_ONLY / SPAN_AND_EVENT — content in trace spans
• true / false — invalid; fall back to NO_CONTENT

For the full mechanics (semconv opt-in, declarative Terraform config, env-var table, enabling/disabling, verification commands), see references/cloud-trace-and-logging.md. For ADK logging docs (log levels, configuration, debugging), fetch https://adk.dev/observability/logging/index.md.

BigQuery Agent Analytics Plugin

Optional plugin that logs structured agent events to BigQuery. Enable with --bq-analytics at scaffold time. See references/bigquery-agent-analytics.md for details.

Third-Party Integrations

ADK supports many third-party observability platforms (via OpenTelemetry or custom instrumentation). The table below covers common ones; the full list is larger (see the pointer below it).

| Platform | Key Differentiator | Setup Complexity | Self-Hosted Option |

|----------|-------------------|-----------------|-------------------|

| AgentOps | Session replays, 2-line setup, replaces native telemetry | Minimal | No (SaaS) |

| Arize AX | Commercial platform, production monitoring, evaluation dashboards | Low | No (SaaS) |

| Phoenix | Open-source, custom evaluators, experiment testing | Low | Yes |

| MLflow | OTel traces to MLflow Tracking Server, span tree visualization | Medium (needs SQL backend) | Yes |

| Monocle | 1-call setup, VS Code Gantt chart visualizer | Minimal | Yes (local files) |

| Weave | W&B platform, team collaboration, timeline views | Low | No (SaaS) |

| Freeplay | Prompt management + evals + observability in one platform | Low | No (SaaS) |

Ask the user which platform they prefer — present the trade-offs and let them choose. Fetch a platform's setup page at https://adk.dev/integrations/<slug>/index.md (slugs for the table above: agentops, arize-ax, phoenix, mlflow-tracing, monocle, weave, freeplay). ADK has more observability integrations (Datadog, Galileo, LangWatch, Latitude, Future AGI, Respan, Zespan, …) — browse the complete, current list at https://adk.dev/integrations/ (observability topic).

Troubleshooting

| Issue | Solution |

|-------|----------|

| No traces in Cloud Trace | Verify fast_api_app.py uses get_fast_api_app(otel_to_cloud=True) (Agent Runtime gates it on GOOGLE_CLOUD_AGENT_ENGINE_ENABLE_TELEMETRY) and the SA has the cloudtrace.agent role |

| Prompt-response data not appearing | Check LOGS_BUCKET_NAME is set; verify SA has storage.objectCreator on the bucket; check app logs for telemetry setup warnings |

| Content in traces/events (unwanted) | OTEL_INSTRUMENTATION_GENAI_CAPTURE_MESSAGE_CONTENT=NO_CONTENT keeps content out of spans/events. NOTE: GCS/BigQuery completions still capture full content — to stop that, remove LOGS_BUCKET_NAME/OTEL_INSTRUMENTATION_GENAI_COMPLETION_HOOK (drop the upload block in service.tf) |

| BigQuery Analytics not logging | Verify plugin is configured in app/agent.py; check BQ_ANALYTICS_DATASET_ID env var is set |

| Third-party integration not capturing spans | Check provider-specific env vars (API keys, endpoints); some providers (AgentOps) replace native telemetry |

| Traces missing tool spans | Tool execution spans appear under execute_tool — check trace explorer filters |

| High telemetry costs | Switch to NO_CONTENT mode; reduce BigQuery retention; disable unused tiers |

Deep Dive: ADK Docs (WebFetch URLs)

For detailed documentation beyond what this skill covers, fetch these pages:

| Topic | URL |

|-------|-----|

| Observability overview | https://adk.dev/observability/index.md |

| Agent activity logging | https://adk.dev/observability/logging/index.md |

| Cloud Trace integration | https://adk.dev/integrations/cloud-trace/index.md |

| BigQuery Agent Analytics | https://adk.dev/integrations/bigquery-agent-analytics/index.md |

Related Skills

• /google-agents-cli-deploy — Deployment targets, CI/CD pipelines, and production workflows
• /google-agents-cli-workflow — Development workflow, coding guidelines, and operational rules
• /google-agents-cli-adk-code — ADK Python API quick reference for writing agent code