Langfuse

Name: Langfuse
Author: pulsemcp

by pulsemcpversion 0.1.3i★ –iRuns on your computer

Registry namecom.pulsemcp/langfuse

Install

Overview

Description from the maker (original English)

MCP server for Langfuse LLM observability — trace and observation analysis.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
UsageiNot measured yet★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs on your computer
Transport: stdio
Category: Search & AI memory
You need to fill in: LANGFUSE_SECRET_KEY, LANGFUSE_PUBLIC_KEY

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 1 of 1 passed
Runs on your computer with your user’s permissions (files, network, apps).
You fill in yourself: LANGFUSE_SECRET_KEY, LANGFUSE_PUBLIC_KEY, LANGFUSE_BASE_URL

Values marked secret are keys to your account. Never share them or paste them into a chat.

You need

npmNode.js installed (for the npx command)

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json

{
  "mcpServers": {
    "langfuse": {
      "command": "npx",
      "args": [
        "-y",
        "langfuse-observability-mcp-server"
      ],
      "env": {
        "LANGFUSE_SECRET_KEY": "your-value",
        "LANGFUSE_PUBLIC_KEY": "your-value",
        "LANGFUSE_BASE_URL": "your-value"
      }
    }
  }
}

Run this in your terminal

claude mcp add langfuse --env LANGFUSE_SECRET_KEY=your-value --env LANGFUSE_PUBLIC_KEY=your-value --env LANGFUSE_BASE_URL=your-value -- npx -y langfuse-observability-mcp-server

Fill in the empty values before running it.

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "langfuse": {
      "command": "npx",
      "args": [
        "-y",
        "langfuse-observability-mcp-server"
      ],
      "env": {
        "LANGFUSE_SECRET_KEY": "your-value",
        "LANGFUSE_PUBLIC_KEY": "your-value",
        "LANGFUSE_BASE_URL": "your-value"
      }
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "langfuse": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "langfuse-observability-mcp-server"
      ],
      "env": {
        "LANGFUSE_SECRET_KEY": "your-value",
        "LANGFUSE_PUBLIC_KEY": "your-value",
        "LANGFUSE_BASE_URL": "your-value"
      }
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.

Your choice stays on this device in a cookie; no account needed.

Values you fill in

LANGFUSE_SECRET_KEY secret required env
Langfuse secret key for authentication.
LANGFUSE_PUBLIC_KEY secret required env
Langfuse public key for authentication.
LANGFUSE_BASE_URL env
Langfuse API base URL.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 7, 2026

✓ Pass
Maker matches the repo
The registry name was verified against the domain pulsemcp.com (the registry checks domain ownership)
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
– Not applicable
Endpoint responds
This one runs on your computer; there is no internet endpoint
– Not applicable
Sign-in with OAuth
Runs on your computer and uses local settings instead
… Not checked yet
No hidden instructions in tool descriptions
Runs on your computer; we can only read tool lists from internet endpoints

Compared with others in Search & AI memoryi

More stars than 0% of the other 7249 servers in this category
Published to the registry more recently than 17% of the other 7249 servers in this category
Basic checks equal to or better than 100% of the other 7249 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is Langfuse safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

You need to fill in: LANGFUSE_SECRET_KEY, LANGFUSE_PUBLIC_KEY

Does it run on my computer or in the cloud?

It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed –, and the latest version (0.1.3) reached the registry 5 months ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Node.js on your computer.

What can I use instead?

In the same category: Context7, Codebase Memory, Exa

Alternatives

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Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

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Computer or cloud★ 64,224MITUpdated today

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Codebase Memory

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Exa

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Runs in the cloud★ 5,213MITUpdated last month

Install

README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

Langfuse MCP Server

MCP server for readonly analysis of Langfuse LLM traces and observations. Designed to help agents deeply inspect trace data, debug LLM pipelines, and analyze costs and latency.

Highlights

Browse and filter traces by name, user, session, tags, timestamps, and environment
Drill into full trace details including all nested observations and scores
List and filter observations by type (GENERATION, SPAN, EVENT), model, level, and more
Automatic truncation of large payloads (>1000 chars) to /tmp files with grep-friendly references
Read-only — no write operations, safe to use without risk of data modification

Capabilities

Tools

Tool	Description
`get_traces`	List traces with filtering and pagination. Returns minimal summary (no I/O fields).
`get_trace_detail`	Get full trace by ID including observations, scores, input/output, and metadata.
`get_observations`	List observations with filtering by traceId, type, level, etc. Returns minimal summary.
`get_observation`	Get full observation by ID including input, output, model parameters, usage, and cost details.

Resources

Resource	Description
`langfuse://config`	Server configuration and status (for debugging)

Large Payload Handling

Trace and observation data often contains very large input/output fields (full prompts, completions, etc.). This server automatically:

Truncates any string field longer than 1000 characters
Saves the full content to a /tmp/langfuse_*.txt file
Includes the file path in the truncated output

Agents can then use grep to search within these files for specific content without loading the entire payload into context.

Configuration

Environment Variables

Variable	Required	Description	Default
`LANGFUSE_SECRET_KEY`	Yes	Langfuse secret key (sk-lf-...)	-
`LANGFUSE_PUBLIC_KEY`	Yes	Langfuse public key (pk-lf-...)	-
`LANGFUSE_BASE_URL`	No	Langfuse API base URL	`https://cloud.langfuse.com`

Claude Desktop Configuration

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

Windows: %APPDATA%\Claude\claude_desktop_config.json

"mcpServers": { "langfuse": { "command": "npx", "args": ["-y", "langfuse-observability-mcp-server"], "env": { "LANGFUSE_SECRET_KEY": "sk-lf-your-secret-key", "LANGFUSE_PUBLIC_KEY": "pk-lf-your-public-key", "LANGFUSE_BASE_URL": "https://us.cloud.langfuse.com" } } } }

Development

# Install dependencies

npm run install-all

Build

npm run build

Development mode

npm run dev

Run functional tests

npm test

Run integration tests

npm run test:integration

Run manual tests (requires .env with real credentials)

npm run test:manual

License

MIT

Langfuse

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

Values you fill in

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Search & AI memoryi

Common questions

Alternatives

Context7

Codebase Memory

Exa

README from the maker

Langfuse MCP Server

Highlights

Capabilities

Tools

Resources

Large Payload Handling

Configuration

Environment Variables

Claude Desktop Configuration

Development

Build

Development mode

Run functional tests

Run integration tests

Run manual tests (requires .env with real credentials)

License