opik-online-eval

opik-online-eval is a skill for Claude Code from comet-ml/opik-claude-code-plugin. It costs 146 tokens per session (2,934 once invoked), scanned A, a copy of opik-online-eval, Apache-2.0.

A production-monitoring setup that applies an automated judge to new Opik traces. A trace is a record of one application interaction; the judge can use a language model or a Python scoring rule.

In plain words
What is it for?
Use it to score issues such as hallucinations or incorrect answers on new production traces, then confirm that the rule is producing scores.
Why use it?
It finds a chosen failure pattern in live traffic instead of relying only on manual review. Sampling, filters, and a spending limit help control which traces are checked and the cost.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: positional $N argument; mentions Claude Code; mentions Codex.

Part of the opik plugin — 10 skills, 2 commands, 1 agent, 8 hooks shipped together

Good fit Use it to score issues such as hallucinations or incorrect answers on new production traces, then confirm that the rule is producing scores.

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Install with agentmods
npx agentmods add skills/comet-ml/opik-claude-code-plugin/opik-online-eval
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add comet-ml/opik-claude-code-plugin --skill opik-online-eval
Clone the repo
git clone --depth 1 https://github.com/comet-ml/opik-claude-code-plugin

Made for: Claude Code.

Or install opik, the plugin that ships this one along with the rest of its 10 skills, 2 commands, 1 agent, 8 hooks.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for opik-online-eval

README.md
[![agentmods](https://agentmods.dev/badge/skills/comet-ml/opik-claude-code-plugin/opik-online-eval/github.svg)](https://agentmods.dev/skills/comet-ml/opik-claude-code-plugin/opik-online-eval)
Your own site
<a href="https://agentmods.dev/skills/comet-ml/opik-claude-code-plugin/opik-online-eval"><img src="https://agentmods.dev/badge/skills/comet-ml/opik-claude-code-plugin/opik-online-eval/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for opik-online-eval

Your own site · 80×15
<a href="https://agentmods.dev/skills/comet-ml/opik-claude-code-plugin/opik-online-eval"><img src="https://agentmods.dev/badge/skills/comet-ml/opik-claude-code-plugin/opik-online-eval.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 146 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,934 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00146 $0.02934
Opus 5.5 $0.00058 $0.01174
Sonnet 5.5 $0.00029 $0.00587
Haiku 4.5 $0.00015 $0.00293

Measured 22d ago against content hash 0611da9b553d, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

opik-online-eval scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 22d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

100% identical to opik-online-eval — 52 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/opik-online-eval/SKILL.md · 137 lines

How it starts

The opening of the file, as written. The whole thing — 137 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Online Eval — Take a Judge Live

Definition of done: an online evaluation rule exists on the project, is enabled, and has scored at least one new trace — confirmed by reading a fresh trace's feedback score, not by the create call returning. The rule scores one failure mode, samples at a rate the project's volume can afford, carries a cost cap, and maps its variables to the fields the traces actually have. If traffic hasn't arrived yet, the done state is "rule live, unverified — watch this filter". If the rule can't be created, stop at the first genuine blocker and return exactly one next step.

Operate: one failure mode per rule, sample before you scale, cap the spend, verify on a real trace — and change no application code. This skill writes to Opik only.

Inputs

The entry point is /opik-online-eval <what to score> ("hallucinations", "the refund-window answer", "refusals"), /opik-online-eval right after /opik-evaluate validated a judge (take that judge live), or /opik-online-eval <project>. Infer the rest; treat these as optional overrides:

  • project (default: configured) · scope (default: trace; span for one model call, thread for whole conversations) · sampling rate (default: 1.0 under ~1k traces/day, else 0.1–0.2) · filters (default: none; typical: an environment or tag filter) · judge model · cost cap (default: set one) · variable mapping (default: input → input, output → output).

Ask only at a genuine, non-inferable blocker (see Blockers).

Activation — the only in-scope work

1. Resolve project, judge, and scope

Confirm Opik is reachable (~/.opik.config or OPIK_API_KEY; otherwise → Blocker). Resolve the project id from a trace or by name. Decide the judge:

  • A judge /opik-evaluate already validated → reuse its prompt and output schema verbatim.
  • A named metric (hallucination, answer relevance, moderation) → a minimal binary judge for that one failure mode (../opik-evaluate/references/write-judge-prompt.md).
  • A mechanical check (JSON valid, contains a disclaimer, latency budget) → a Python metric rule, not a judge.

Read the full file on GitHub · 137 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 22d ago First seen · 137 lines · 146 tokens per session scan A 0611da9b553d

Subscribe to this mod's changes

opik-online-eval is a skill published in the GitHub repository comet-ml/opik-claude-code-plugin (23 stars, last pushed 7d ago), licensed Apache-2.0. It adds 146 tokens to every session and 2,934 once invoked, about $0.0006 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to opik-online-eval, differing in 52 lines, and is treated as a copy.

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