MCP Server Langfuse

What langfuse/mcp-server-langfuse MCP server does

langfuse/mcp-server-langfuse MCP server connects an MCP client to prompts stored in Langfuse Prompt Management. It supports prompt discovery and retrieval for both text and chat prompts, exposing the results through the MCP Prompts specification and through tools for clients without prompt-capability support.

The server is focused on reading and compiling prompts rather than editing them. Listing returns available prompt names and their arguments. Retrieval selects a prompt by name and applies the variables supplied by the client.

How it works

The MCP prompt interface provides prompts/list for discovery and prompts/get for retrieving a prompt. The server also exposes matching get-prompts and get-prompt tools. The tool form of retrieval requires a name and accepts an optional JSON arguments object containing prompt variables.

List operations can use a cursor for pagination. To determine the arguments associated with each prompt, the server fetches prompts individually in the background. Retrieved Langfuse text and chat prompts are transformed into MCP prompt objects, and supplied variables are used during compilation.

Only prompts carrying the production label are returned. The implementation treats all discovered arguments as optional, and argument descriptions are not included because Langfuse variables do not provide the specification required for them.

Setup and configuration

The repository is built locally with npm. Run npm install, then npm run build; the resulting entry point is build/index.js. An MCP client should launch that file with Node.js.

The server requires three environment variables: LANGFUSE_PUBLIC_KEY, LANGFUSE_SECRET_KEY, and LANGFUSE_BASEURL. The first two authenticate requests to Langfuse, while the base URL identifies the Langfuse endpoint.

For Claude Desktop, add a server entry whose command is node, whose argument points to the built build/index.js, and whose environment contains the Langfuse credentials and base URL. Cursor can also run the server as a command with the same environment variables and Node.js entry point.

Tools and capabilities

• get-prompts lists available production prompts and supports an optional pagination cursor.
• get-prompt retrieves and compiles one prompt using its required name and optional JSON variables.
• prompts/list provides MCP-native prompt discovery with pagination support.
• prompts/get provides MCP-native prompt retrieval for text and chat prompts.

The tool endpoints mirror the MCP prompt operations, which gives clients an alternative when they do not implement the prompt capability directly.

Limitations and notes

langfuse/mcp-server-langfuse MCP server is described as a work in progress. Prompt listing is less efficient because the server retrieves prompts individually to extract their arguments. Returned arguments are marked optional, and no variable descriptions are supplied. Prompt visibility is also restricted to entries labeled production; prompts without that label will not appear in discovery or retrieval results.