opik

Opik Claude Code Plugin

Log Claude Code sessions to Opik for LLM observability, plus skills and agents for building observable AI applications.

Features

• Session Tracing: Automatically log Claude Code sessions as Opik traces
• Span Tracking: Each tool call becomes a span within the trace
• Subagent Support: Nested agent calls are tracked with parent-child relationships
• Skills: Built-in knowledge for LLM observability, tracing, and evaluation
• Agents: Code review agent for agent architecture best practices

How Tracing Works

We trigger tracing for everything done in Claude Code, but don't slow you down.

Each conversation turn becomes an Opik trace. Tool calls, thoughts, and responses become spans. Subagent invocations are nested under their parent Task span.

Installation

From within Claude Code:

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

Then install the plugin:

/plugin install opik

Local Install (for contributors)

If you've cloned the repo locally, add it as a marketplace and install from there:

/plugin marketplace add /path/to/opik-claude-code-plugin
/plugin install opik

Important: Restart any running Claude Code sessions after installation. Hooks only load when a session starts.

Configuration

Run the Opik CLI to configure your connection:

pip install opik
opik configure

This creates ~/.opik.config with your API URL, key, and workspace.

Optional Environment Variables

export OPIK_CC_PROJECT="my-project"         # Project name (default: claude-code)
export OPIK_CC_WORKSPACE="my-workspace"     # Workspace override (default: OPIK_WORKSPACE / ~/.opik.config)
export OPIK_CC_TRUNCATE_FIELDS="false"      # Don't truncate large fields

All plugin env vars use the OPIK_CC_ prefix to avoid conflicts with standard Opik SDK variables.

OPIK_CC_WORKSPACE and OPIK_CC_PROJECT let you send Claude Code traces to a different workspace/project than the rest of your Opik setup, without touching the global OPIK_WORKSPACE / project_name in ~/.opik.config used by the Opik SDK. Both can also be set in ~/.opik.config via the plugin-scoped cc_workspace and cc_project keys:

[opik]
workspace = my-sdk-workspace      # used by the Opik SDK
project_name = my-sdk-project     # used by the Opik SDK
cc_workspace = my-cc-workspace        # used only by the Claude Code plugin
cc_project_name = my-cc-project       # used only by the Claude Code plugin

Note: for backward compatibility, if cc_project_name is not set the plugin still falls back to the shared project_name key.

External Trace Linking

Link Claude Code sessions to existing Opik traces (useful for embedding Claude Code in larger workflows):

export OPIK_CC_PARENT_TRACE_ID="your-trace-id"  # Attach to existing trace
export OPIK_CC_ROOT_SPAN_ID="your-span-id"      # Set parent span for all Claude Code spans

MCP Server Setup

The Opik MCP server provides Claude with tools to interact with your Opik data - query traces, analyze experiments, and access evaluation results directly in conversation.

For Opik Cloud

Add to your ~/.claude.json:

{
  "mcpServers": {
    "opik": {
      "command": "npx",
      "args": ["-y", "opik-mcp", "--apiKey", "YOUR_OPIK_API_KEY"]
    }
  }
}

Replace YOUR_OPIK_API_KEY with your API key from comet.com.

For Self-Hosted Opik

{
  "mcpServers": {
    "opik": {
      "command": "npx",
      "args": ["-y", "opik-mcp", "--apiBaseUrl", "http://localhost:5173/api"]
    }
  }
}

Adjust the apiBaseUrl to match your Opik instance.

Pre-configured Templates

Copy-ready configurations are available in mcp-configs/mcp-servers.json.

Commands

/opik:trace-claude-code - Claude Code Session Tracing

Enable/disable automatic tracing of your Claude Code sessions to Opik.

/opik:trace-claude-code start                 # Enable tracing for this project
/opik:trace-claude-code start --debug         # Enable tracing + debug logging
/opik:trace-claude-code stop                  # Disable tracing for this project
/opik:trace-claude-code status                # Check project + global + effective state

/opik:trace-claude-code start --global        # Enable tracing for all projects
/opik:trace-claude-code stop --global         # Disable tracing globally

Tracing state is stored in .claude/.opik-tracing-enabled (project) or ~/.claude/.opik-tracing-enabled (global). Resolution order (first match wins):