langfuse-trace-view

name	langfuse-trace-view
description	View Langfuse trace details. Use when checking specific trace input/output, debugging LLM calls, or analyzing costs.
license	MIT
compatibility	Node.js 18+ (native fetch required)
metadata	{"author":"neuradex","category":"observability"}
allowed-tools	["Bash(npx tsx *scripts/langfuse-trace-view.ts*)"]

Langfuse Trace View

Display detailed information for a specific trace.

Setup

Set the following environment variables before use:

Variable	Required	Description
LANGFUSE_PUBLIC_KEY	Yes	Langfuse public key
LANGFUSE_SECRET_KEY	Yes	Langfuse secret key
LANGFUSE_HOST or LANGFUSE_BASE_URL	No	Langfuse host URL (default: https://us.cloud.langfuse.com)

When to Use

• Checking specific trace details
• Viewing LLM input/output
• "Show me the details of this trace"
• Investigating by trace ID

Commands

1. Get Trace Details

npx tsx scripts/langfuse-trace-view.ts <traceId>

2. JSON Output

npx tsx scripts/langfuse-trace-view.ts <traceId> --json

Output Example

Langfuse Trace Detail
=====================

ID:        abc123-def456-ghi789
Name:      librarian/chat
Timestamp: 2025-01-15 10:30:45
User ID:   user-123
Session:   lb:session-456
Latency:   1234ms
Cost:      $0.0150
Tags:      env:production

Metadata:
{
  "projectId": "project-123",
  "organizationId": "org-456"
}

Input:
{
  "userMessage": "Search the knowledge base"
}

Output:
{
  "response": "Here are the search results..."
}

Observations (3):
--------------------------------------------------------------------------------

[GENERATION] llm-call
  Time: 10:30:46  Model: gpt-4o  Cost: $0.0120  Tokens: in:150 out:200
  Input: {"role": "user", ...}
  Output: Here are the search results...

[SPAN] tool-execution
  Time: 10:30:47  Model: -  Cost: -  Tokens: -

Fields

Field	Description
ID	Trace ID
Name	Trace name
Timestamp	Creation timestamp
User ID	User ID
Session	Session ID
Latency	Processing time (ms)
Cost	Estimated cost
Tags	Tag list
Metadata	Metadata
Input	Trace input
Output	Trace output
Observations	Child spans (Generation, Span, etc.)