@solaraai/mcp-server-langfuse

Model Context Protocol (MCP) server that exposes your Langfuse prompts as standard MCP prompts and CLI tools. Now installable in one line:

npx -y @solaraai/mcp-server-langfuse  # requires LANGFUSE_* env vars

Features

MCP Prompt capability

| Endpoint | Description | | ------------------- | ----------------------------------------------------- | | prompts/list | Paginated list of available prompts (production label) | | prompts/get | Fetch + compile a single prompt (text or chat) |

CLI / Tool equivalents (for hosts that don’t implement prompt-capability)

| Tool name | Purpose | | ---------------------- | ------------------------------------------------------------- | | get-prompts | List prompts (same as prompts/list) | | get-prompt | Fetch & compile one prompt | | get-prompts-bulk | Fetch & compile multiple prompts in one call | | edit-prompt | Create or update (new version) a prompt | | publish-prompt | Tag a prompt version as production or any label | | list-prompt-versions | Show all versions/labels/tags for a prompt | | get-prompt-metadata | Fetch metadata for a version/label (no compilation) | | search-prompts | Search by name / label / tag | | validate-prompt | Linter for prompt templates (unclosed vars, chat JSON etc.) |

Quick start

# 1. Export your Langfuse keys (or add them to your MCP config)
export LANGFUSE_PUBLIC_KEY="pk-..."
export LANGFUSE_SECRET_KEY="sk-..."
export LANGFUSE_BASEURL="https://cloud.langfuse.com"   # optional, defaults

# 2. Launch via npx
npx -y @solaraai/mcp-server-langfuse

The server runs on STDIO, so any MCP host that supports stdio transports (e.g. Cursor, Claude Desktop) can spawn it with the same npx command.

Example host configuration (Cursor)

{
  "mcpServers": {
    "langfuse-prompts": {
      "command": "npx",
      "args": ["-y", "@solaraai/mcp-server-langfuse"],
      "env": {
        "LANGFUSE_PUBLIC_KEY": "pk-...",
        "LANGFUSE_SECRET_KEY": "sk-...",
        "LANGFUSE_BASEURL": "https://cloud.langfuse.com"
      },
      "transportType": "stdio"
    }
  }
}

Development

git clone https://github.com/solaraai/mcp-server-langfuse
cd mcp-server-langfuse
npm install
npm run build  # emits ./build/index.js

# Run locally
LANGFUSE_PUBLIC_KEY=... node ./build/index.js

# Or test via MCP inspector
npx @modelcontextprotocol/inspector npx -y @solaraai/mcp-server-langfuse

Publishing

Scoped packages default to private. We ship it public:

npm run deploy   # builds & publishes with --access public

Limitations

• Only prompt versions with the production label are returned by prompts/list for safety (use search-prompts or pass label param to query others).
• Variable metadata (required/optional, description) isn’t available from the Langfuse API, so arguments are listed without rich docs.

Contributions welcome – open an issue or PR!