@jurislm/langfuse-mcp

MCP (Model Context Protocol) server for Langfuse — provides 50 tools for prompt management, observability, instance/organization management, and metrics tracking via natural language.

Tools (50)

Prompt Management (6 tools)

• listPrompts — List and filter prompts with pagination, labels, tags
• getPrompt — Fetch a specific prompt version with resolved dependencies
• createTextPrompt — Create a text prompt version (supports {{variable}} syntax)
• createChatPrompt — Create a chat prompt with role-based messages
• getPromptUnresolved — Fetch a prompt without resolving dependencies (for debugging composition)
• updatePromptLabels — Update labels for a prompt version (labels are unique across versions)

Traces (2 tools)

• listTraces — List traces with pagination and optional filters (name, userId, tags, timestamps)
• getTrace — Get a single trace with full details, observations, and scores

Observations (2 tools)

• listObservations — List observations (generations, spans, events) with filters by type and name
• getObservation — Get a single observation with complete details (input, output, model, usage, duration)

Scores (2 tools)

• createScore — Create a score for a trace or observation (for evals, feedback, quality metrics)
• listScores — List scores with pagination and optional filters

Sessions (1 tool)

• listSessions — List sessions that group related traces together across time ranges

Datasets (8 tools)

• listDatasets — List datasets for evals and benchmarking with search and pagination
• getDataset — Get dataset details with metadata and item counts
• createDataset — Create a new dataset for evals or benchmarking
• listDatasetItems — List items in a dataset with pagination (input/output pairs)
• createDatasetItem — Add an input/output pair to a dataset for eval testing
• getDatasetItem — Get a single dataset item by ID
• listDatasetRuns — List eval execution runs (traces using this dataset)
• getDatasetRun — Get details of a dataset run (eval execution)

Metrics (2 tools)

• getDailyMetrics — Get daily metrics for traces and observations (latency, tokens, scores, cost)
• getUsageSummary — Get usage summary for a time period (total traces, observations, tokens, cost)

Score Configurations (4 tools)

• listScoreConfigs — List all score configurations (custom score names and data types)
• getScoreConfig — Get details of a score configuration including name, data type, and categories
• createScoreConfig — Create a new score configuration for custom scoring metrics
• updateScoreConfig — Update an existing score configuration

Project (1 tool)

• getProject — Get current project details (name, API keys, limits, usage)

Instance Management (8 tools)

• listInstances — List all Langfuse instances with pagination
• getInstance — Get details of a specific instance
• createInstance — Create a new instance
• updateInstance — Update an existing instance
• deleteInstance — Delete an instance
• listInstanceEvents — List events for an instance
• getInstanceStatus — Get health and status information
• configureInstanceSettings — Configure advanced settings

Organization Projects (5 tools)

• listOrganizationProjects — List all projects within an organization
• getOrganizationProject — Get details of a specific project
• createOrganizationProject — Create a new project in an organization
• updateOrganizationProject — Update an existing project
• deleteOrganizationProject — Delete a project from an organization

Organization API Keys (3 tools)

• listOrganizationApiKeys — List all API keys for an organization
• createOrganizationApiKey — Create a new API key
• deleteOrganizationApiKey — Delete an API key

Organization Memberships (6 tools)

• listOrganizationMembers — List all members of an organization
• addOrganizationMember — Add a new member to an organization
• updateOrganizationMember — Update a member's role or permissions
• removeOrganizationMember — Remove a member from an organization
• listProjectMembers — List members with access to a specific project
• updateProjectMember — Update a member's access level for a project

Setup

Environment Variables

# Public API (Required for Prompt Management, Traces, Observations, Scores, Sessions, etc.)
LANGFUSE_PUBLIC_KEY=pk-lf-...
LANGFUSE_SECRET_KEY=sk-lf-...

# Instance/Organization Management APIs (Required for Instance and Organization tools)
LANGFUSE_ADMIN_API_KEY=adm-lf-...

# Optional: Organization-specific API key for additional org-level tools
LANGFUSE_ORG_API_KEY=org-lf-...

# Optional: API Server (defaults to https://cloud.langfuse.com)
LANGFUSE_HOST=https://cloud.langfuse.com
# US region: https://us.cloud.langfuse.com

Usage with Claude Code (via npx)

Add to your MCP configuration (.mcp.json or ~/.claude/settings.json):

{
  "mcpServers": {
    "langfuse": {
      "command": "bunx",
      "args": ["@jurislm/langfuse-mcp@latest"],
      "env": {
        "LANGFUSE_PUBLIC_KEY": "pk-lf-...",
        "LANGFUSE_SECRET_KEY": "sk-lf-...",
        "LANGFUSE_HOST": "https://cloud.langfuse.com"
      }
    }
  }
}

Note: Requires Bun installed globally (curl -fsSL https://bun.sh/install | bash).

Usage with Claude Code Plugin (jurislm-tools)

If you use the jurislm-tools Claude Code plugin, jt:langfuse is included:

/plugin marketplace update jurislm-tools

Then set environment variables in ~/.zshenv:

export LANGFUSE_PUBLIC_KEY=pk-lf-...
export LANGFUSE_SECRET_KEY=sk-lf-...
export LANGFUSE_HOST=https://us.cloud.langfuse.com

Development

bun install
bun run dev        # Run locally (stdio transport)
bun run build      # Build to dist/
bun run typecheck  # TypeScript check
bun run lint       # ESLint (max-warnings=0)

License

MIT