Langfuse MCP server

Langfuse MCP Server

<!-- mcp-name: io.github.avivsinai/langfuse-mcp -->

Usage: 12,518 PyPI downloads last month (pypistats, 2026-08-19). v0.10.1.

Local MCP server and skill for Langfuse. Debug traces, sessions, and exceptions from Claude Code, Codex, Cursor, or any MCP client.

Why this instead of native Langfuse MCP?

Use this for local debug: first-class traces, sessions, and exceptions; route-decision tools; compact / file-dump output; plus the included langfuse skill.

Use official Langfuse MCP for hosted, zero-install access to the broader API (score writes, comments, models, media).

As of June 2026:

langfuse-mcp for local debug. Native MCP for hosted breadth.

See a failing trace in 2 minutes

Install is uvx langfuse-mcp plus Langfuse API keys — Quick Start for Claude Code, Codex, Cursor, or Docker.

After the client restarts, ask:

find exceptions in the last day

That maps to existing tools:

find_exceptions(age=1440, group_by="file")
find_exceptions_in_file(filepath="<file from the grouping>", age=1440)
get_exception_details(trace_id="<trace_id from the file results>")

findexceptions returns {group, count, observationid, traceid} (top 50 groups) — each group carries a representative observation/trace ID, and findexceptionsinfile also yields full error records. Then optionally:

fetch_trace(trace_id="<trace_id>", include_observations=true)

The exception tools detect errors by observation level == "ERROR" (strict; a non-empty statusmessage alone does not count). Counts describe error-level observations, not individual exception events — geterrorcount returns exceptioncount: null for that reason. Exception details come from recorded metadata (exception.type / exception.message / exception.stacktrace, top-level or under metadata.attributes); absent values are null. Results are not a point-in-time snapshot.

Project Links

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Quick Start

Shortened. The full README is on GitHub.