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Observability for Claude Code with Opik

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Claude Code sessions can be logged to Opik in two ways: with the Opik Claude Code plugin, which hooks into Claude Code directly and captures every turn, tool call and subagent with full content, or through Claude Code’s native OpenTelemetry export, which sends spans to Opik’s OTLP endpoint. Most teams should start with the plugin.

Quick start

Inside Claude Code:

/plugin marketplace add comet-ml/opik-claude-code-plugin
/plugin install opik

In a terminal, then restart Claude Code:

$pip install opik && opik configure

Back inside Claude Code:

/opik:trace-claude-code start

Your next turn appears as a trace in the claude-code project in Opik. The rest of this page explains the two options in full, how to route traces to a project or workspace, and how to validate.

When this guide applies

Use this guide if you want to review Claude Code conversations in Opik: what developers asked, what the model answered, which tools ran, how subagents nested, and what each turn cost.

This guide covers telemetry flowing from Claude Code to Opik. For the other direction, letting Claude Code read your traces, score outputs and run evaluations from chat, register the Opik MCP server with it. One command, uvx opik mcp configure, installs the server and the Opik skills. The two are independent, and you can use either or both.

Looking to reduce Claude Code spend rather than review sessions?

Opik shows you what Claude Code did. If the question is where the tokens went and how to spend fewer of them, that is Cost Intelligence: every Claude Code API call captured on the wire and attributed to system prompt, tool schemas, MCP servers, skills, memory and user input, per user and per repository, with policy controls that typically cut spend by 15% to 30%. Only counts and metadata leave the machine, never content. Claude Code is Cost Intelligence’s primary agent, and it runs side by side with the Opik plugin.

Choose a path

Opik plugin (recommended)Native OTel export
SetupTwo slash commands in Claude CodeEnvironment variables before every session
Prompt, response and tool contentCaptured by defaultRedacted by default; response text needs a beta flag and only in non-interactive runs
SubagentsNested under the parent Task spanFlat claude_code.* spans
Project / workspace routingOPIK_CC_PROJECT, OPIK_CC_WORKSPACEprojectName and Comet-Workspace headers
Fleet rolloutPlugin marketplace, or Claude managed settingsManaged settings can set the env vars
StatusGAClaude Code tracing is beta

Option 1: Opik Claude Code plugin

The opik-claude-code-plugin turns each conversation turn into an Opik trace. Tool calls, thoughts and responses become spans, and subagent invocations nest under their parent Task span.

Install

From inside Claude Code:

/plugin marketplace add comet-ml/opik-claude-code-plugin
/plugin install opik

Restart any running Claude Code session; hooks only load when a session starts.

Configure the connection

$pip install opik
$opik configure

This writes ~/.opik.config with your Opik URL, API key and workspace. Self-hosted and Enterprise deployments enter their own URL at the prompt.

Turn tracing on

/opik:trace-claude-code start            # this project
/opik:trace-claude-code start --global   # every project on this machine
/opik:trace-claude-code status

Traces land in the claude-code project by default. To route them elsewhere without touching the Opik SDK settings the rest of your code uses:

$export OPIK_CC_PROJECT="my-project"
$export OPIK_CC_WORKSPACE="my-workspace"

or add cc_project_name / cc_workspace under [opik] in ~/.opik.config.

Embed Claude Code in a larger trace

If Claude Code runs inside a workflow you already trace with Opik, attach its spans to that trace:

$export OPIK_CC_PARENT_TRACE_ID="<existing-trace-id>"
$export OPIK_CC_ROOT_SPAN_ID="<parent-span-id>"

What you see in Opik

Open the project and pick a trace: the user prompt is the trace input, the assistant’s final answer is the output, and each tool call is a span with its input and result. The Threads tab groups turns from the same session. Token usage and cost are recorded on each LLM span.

Option 2: Native OpenTelemetry export

Claude Code can emit OTel metrics, events and, in beta, trace spans. Opik ingests the trace spans only. Use this path when you already ship Claude Code telemetry to an OTel collector and want Opik as one more destination, or when you cannot install plugins.

Without CLAUDE_CODE_ENHANCED_TELEMETRY_BETA=1 Claude Code sends only metrics and events, and nothing appears in Opik. Prompt, tool I/O and assistant output are redacted by default; the flags in this section un-redact them. Assistant output on spans additionally requires the detailed-tracing beta, which is available for the Claude Agent SDK and non-interactive claude -p runs but gated in interactive sessions. If you need full content in interactive sessions, use the plugin.

Set these before starting Claude Code (Opik Cloud shown; swap the endpoint for your deployment, see the Opik OpenTelemetry overview):

$# 1. Enable telemetry and trace-span emission
$export CLAUDE_CODE_ENABLE_TELEMETRY=1
$export CLAUDE_CODE_ENHANCED_TELEMETRY_BETA=1
$
$# 2. Export traces to Opik
$export OTEL_TRACES_EXPORTER=otlp
$export OTEL_EXPORTER_OTLP_PROTOCOL=http/protobuf
$export OTEL_EXPORTER_OTLP_ENDPOINT=https://www.comet.com/opik/api/v1/private/otel
$export OTEL_EXPORTER_OTLP_HEADERS='Authorization=<your-api-key>,Comet-Workspace=<your-workspace>,projectName=<your-project-name>'
$
$# 3. Un-redact prompt and tool input/output
$export OTEL_LOG_USER_PROMPTS=1
$export OTEL_LOG_TOOL_DETAILS=1
$export OTEL_LOG_TOOL_CONTENT=1
$
$# 4. Assistant output on spans (detailed-tracing beta, non-interactive only)
$export ENABLE_BETA_TRACING_DETAILED=1
$export BETA_TRACING_ENDPOINT=https://www.comet.com/opik/api/v1/private/otel

Spans arrive as claude_code.interaction (one per prompt) with nested claude_code.llm_request and claude_code.tool spans. Opik maps their content to trace and span input/output and calculates cost from the model and token attributes.

For the full variable reference, endpoint modes and validation steps, see Claude Agent SDK and Claude Code OpenTelemetry.

Validation

  1. Run a short Claude Code turn that uses a tool, for example “list the files in this directory”.
  2. Open the target project in Opik (claude-code for the plugin, your projectName for OTel).
  3. Confirm the trace carries content:
    • Plugin: the trace input is your prompt and the trace output is the assistant’s answer.
    • Native OTel: the trace is named claude_code.interaction, its input is your prompt, and the model’s response is on the claude_code.llm_request spans (with model, tokens and cost). The trace-level output stays empty on this path. Tool calls appear as claude_code.tool spans with their input and result.

Source references