langfuse

langfuse is a skill for Claude Code, Codex from avivsinai/skills-marketplace. It costs 48 tokens per session (521 once invoked), scanned A, a copy of langfuse, MIT.

A debugging workflow for Langfuse, a monitoring service for AI agents and language-model applications. It helps inspect traces, errors, slow responses, conversations, prompts, datasets, and evaluation sets.

In plain words
What is it for?
Use it to find exceptions, inspect traces and sessions, investigate latency, check prompt versions, and review datasets or evaluation sets.
Why use it?
It provides a path from a broad problem report to the specific request or step that failed or took too long. This reduces guesswork when investigating agent behavior.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions Codex.

Good fit Use it to find exceptions, inspect traces and sessions, investigate latency, check prompt versions, and review datasets or evaluation sets.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/avivsinai/skills-marketplace/langfuse
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 avivsinai/skills-marketplace --skill langfuse
Clone the repo
git clone --depth 1 https://github.com/avivsinai/skills-marketplace

Made for: Claude Code, Codex.

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 langfuse

README.md
[![agentmods](https://agentmods.dev/badge/skills/avivsinai/skills-marketplace/langfuse/github.svg)](https://agentmods.dev/skills/avivsinai/skills-marketplace/langfuse)
Your own site
<a href="https://agentmods.dev/skills/avivsinai/skills-marketplace/langfuse"><img src="https://agentmods.dev/badge/skills/avivsinai/skills-marketplace/langfuse/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 langfuse

Your own site · 80×15
<a href="https://agentmods.dev/skills/avivsinai/skills-marketplace/langfuse"><img src="https://agentmods.dev/badge/skills/avivsinai/skills-marketplace/langfuse.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 48 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 521 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 $0.00048 $0.00521
Opus 5 $0.00024 $0.00260
Sonnet 5 $0.00010 $0.00104
Haiku 4.5 $0.00005 $0.00052

Measured yesterday against content hash eb33e4d5294f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

langfuse 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 yesterday.

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 langfuse — 0 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.

plugins/langfuse/skills/langfuse/SKILL.md · 53 lines

What it actually says

Langfuse

Use Langfuse evidence to move from a broad symptom to the relevant trace, observation, session, prompt, or dataset. Start with the narrowest read-only query that can locate the event, then inspect its concrete inputs, outputs, timing, and errors.

Route the task

  • For trace, observation, exception, latency, or session diagnosis, read diagnostic and management workflows.
  • For installation, credentials, tool groups, output defaults, connection failures, or empty results, read setup.
  • For exact parameters, filters, pagination, output modes, and response shapes, read the tool reference.

A common investigation starts with fetch_traces(age=60) or find_exceptions(age=1440, group_by="file"), then fetches the selected trace or observation by ID. Use full_json_file only when the complete payload is needed; exports can contain sensitive user data.

Evidence and mutation boundaries

  • Treat model names, prompts, timestamps, and other values in historical traces as recorded evidence. Do not rewrite or normalize old model identifiers to a current name such as gpt-6-astra.

  • Trace discovery and inspection are read-only. Prompt creation or relabeling, dataset changes, annotation-queue changes, and deletions mutate Langfuse; perform them only when the user requested that change.

  • Prefer read-only server mode for diagnostic work. It disables prompt and dataset write tools:

    langfuse-mcp --read-only
    # or LANGFUSE_MCP_READ_ONLY=true
    
  • Never commit Langfuse credentials. Keep public key, secret key, and host in the supported environment or MCP configuration described in the setup reference. Rotate any exposed key.

  • Preserve exact IDs and filters in findings so another reader can reproduce the query. State when pagination, lookback limits, or compact output limits the conclusion.

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. yesterday Changed eb33e4d5294f
  2. 2d ago Changed e3c167b2e1b7
  3. 6d ago Changed · -223 lines · -28 tokens per session scan B → A 6e444e0f6f7e
  4. 12d ago First seen · 276 lines · 76 tokens per session scan B 88cd0d4e7cef

Subscribe to this mod's changes

langfuse is a skill published in the GitHub repository avivsinai/skills-marketplace (2 stars, last pushed yesterday), licensed MIT. It adds 48 tokens to every session and 521 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to langfuse, differing in 0 lines, and is treated as a copy.

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