langfuse

Query Langfuse data via CLI and retrieve Langfuse documentation for LLM observability workflows.

Updated Sep 11, 2026
One-click install
npx skills add https://github.com/celeroncoder/skills --skill langfuse-celeroncoder
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: langfuse
Source: https://github.com/celeroncoder/skills/tree/main/langfuse
Command: npx skills add https://github.com/celeroncoder/skills --skill langfuse-celeroncoder

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill requires langfuse-cli, and includes references (resource) components.

What problem does it solve? Working with Langfuse requires up-to-date knowledge of its APIs, SDKs, and documentation, which change frequently. This Skill gives you programmatic access to Langfuse data (traces, prompts, datasets, scores, sessions) through the langfuse-cli and reliable methods to fetch current Langfuse documentation, so you never implement against outdated information. ## Core Features & Use Cases - CLI-Based API Access: Query and modify any Langfuse resource (traces, prompts, datasets, scores, sessions) using npx langfuse-cli with schema discovery and credential setup via environment variables. - Documentation Retrieval: Access Langfuse docs through the llms.txt index, markdown page fetching, and a search API that also indexes GitHub issues and discussions. - Use-Case Reference Guides: Follow dedicated guides for instrumenting applications, migrating prompts to Langfuse, capturing user feedback as scores, upgrading SDKs, and performing systematic error analysis on traces. - Use Case: You want to debug why your LLM app produces bad outputs. The Skill pulls traces via the CLI, guides you through the 5-step error analysis process, creates annotation queues, and links you directly to the Langfuse UI. ## Quick Start Ask the agent to list your recent Langfuse traces or fetch the Langfuse documentation page for the feature you are working on.

Frequently Asked Questions about langfuse

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I query Langfuse traces from the command line?▼

Use `npx langfuse-cli api traces list` after setting LANGFUSE_PUBLIC_KEY, LANGFUSE_SECRET_KEY, and LANGFUSE_HOST environment variables. Run `npx langfuse-cli api __schema` to discover all available resources and `--help` on any resource or action for arguments.

How do I migrate hardcoded prompts to Langfuse?▼

Scan your codebase for prompts, convert variables to {{var}} double-brace syntax, create prompts via `langfuse.create_prompt()` with a production label, then refactor code to use `langfuse.get_prompt()` with `.compile()`. Complex Jinja logic like conditionals must move into application code.

Does Langfuse support capturing user feedback like thumbs up or down?▼

Yes, feedback is stored as scores on traces. Use LangfuseWeb with only the public key in frontend code for explicit feedback, or `langfuse.create_score()` server-side for implicit signals like retries or copies. Always set dataType explicitly for boolean scores.

How do I upgrade the Langfuse Python SDK from v3 to v4?▼

Fetch the official migration guide at langfuse.com first, then replace start_span/start_generation with start_observation, replace update_current_trace with propagate_attributes, and move release and environment settings to environment variables. Enable debug logging to catch dropped spans.

Why are my Langfuse traces not showing up?▼

Common causes include missing `langfuse.flush()` before script exit, importing Langfuse before environment variables load, or importing the OpenAI client before Langfuse setup. Verify credentials with a test call to /api/public/projects and check for a 200 status.

What are the limitations of Langfuse prompt templating?▼

Langfuse only supports simple {{variable}} substitution with no conditionals, loops, or filters. Pre-compute conditional content and formatted lists in your code and pass them as variables, or compile templates client-side with Jinja2 at the cost of losing Playground preview.