{ "slug": "com-pulsemcp-langfuse", "name": "com.pulsemcp/langfuse", "title": "langfuse", "description": "MCP server for Langfuse LLM observability — trace and observation analysis.", "version": "0.1.3", "publishedAt": "2026-06-17T03:55:53.642447Z", "updatedAt": "2026-06-17T03:55:53.642447Z", "repoUrl": "https://github.com/pulsemcp/mcp-servers", "websiteUrl": null, "namespace": { "type": "domain", "owner": "pulsemcp.com" }, "kind": "local", "packages": [ { "registryType": "npm", "identifier": "langfuse-observability-mcp-server", "version": "0.1.3", "transport": "stdio", "runtimeHint": "npx" } ], "remotes": [], "envVars": [ { "name": "LANGFUSE_SECRET_KEY", "isSecret": true, "isRequired": true, "description": "Langfuse secret key for authentication." }, { "name": "LANGFUSE_PUBLIC_KEY", "isSecret": true, "isRequired": true, "description": "Langfuse public key for authentication." }, { "name": "LANGFUSE_BASE_URL", "isSecret": false, "isRequired": false, "description": "Langfuse API base URL." } ], "category": "monitoring", "subcategory": "observability", "company": "", "categoryAuto": true, "checks": [ { "id": "source-linked", "label": "Source repository linked", "result": "pass", "detail": "https://github.com/pulsemcp/mcp-servers" }, { "id": "version-pinned", "label": "Version pinned", "result": "pass", "detail": "Every package has an explicit version" }, { "id": "secrets-requested", "label": "Secrets requested", "result": "info", "detail": "Asks for 2 secrets: LANGFUSE_SECRET_KEY, LANGFUSE_PUBLIC_KEY" }, { "id": "known-registry", "label": "Known package registry", "result": "pass", "detail": "All packages come from npm, PyPI, OCI, NuGet or MCPB" }, { "id": "namespace", "label": "Namespace ownership", "result": "info", "detail": "Name verified via domain pulsemcp.com" }, { "id": "meta-text", "label": "Registry text aimed at the AI", "result": "pass", "detail": "Description and settings contain no hidden characters or instructions to the AI" }, { "id": "install-scripts", "label": "Install scripts", "result": "pass", "detail": "langfuse-observability-mcp-server@0.1.3 runs nothing at install" }, { "id": "code-flags", "label": "Code red flags", "result": "pass", "detail": "Read 38 files in langfuse-observability-mcp-server@0.1.3: no obfuscation, encoded execution, credential reads or data-collection endpoints found" }, { "id": "ai-text", "label": "Text aimed at the AI", "result": "pass", "detail": "No hidden characters or instructions to the AI in 38 files, including comments and the README" } ], "scannedAt": "2026-10-29", "level": "Scanned", "install": [ { "label": "Claude Desktop (npm)", "kind": "claude_desktop_json", "text": "{\n \"mcpServers\": {\n \"langfuse\": {\n \"command\": \"npx\",\n \"args\": [\n \"-y\",\n \"langfuse-observability-mcp-server@0.1.3\"\n ],\n \"env\": {\n \"LANGFUSE_SECRET_KEY\": \"\",\n \"LANGFUSE_PUBLIC_KEY\": \"\"\n }\n }\n }\n}" } ], "curated": true, "stars": 81, "archived": false, "pushedAt": "2026-10-09T17:32:15Z", "review": { "package": "langfuse-observability-mcp-server", "version": "0.1.3", "at": "2026-10-31", "files": 36, "lines": 1377, "verdict": "pass-with-notes", "summary": "Read-only access to your Langfuse traces and observations, sent only to Langfuse Cloud or the self-hosted URL you set. Your Langfuse keys go only there. Long trace contents are saved as plain-text files in /tmp and never deleted, which matters if your traces hold sensitive prompts or user data.", "hosts": [ { "host": "cloud.langfuse.com (or LANGFUSE_BASE_URL)", "when": "only when a tool is called", "sends": "GET requests to /api/public/traces and /api/public/observations with filter parameters and Basic auth (public:secret key)" } ], "env": [ { "name": "LANGFUSE_SECRET_KEY", "sent_to": "LANGFUSE_BASE_URL (Basic auth header); only shown as '***configured***' in the config resource" }, { "name": "LANGFUSE_PUBLIC_KEY", "sent_to": "LANGFUSE_BASE_URL (Basic auth header)" }, { "name": "LANGFUSE_BASE_URL", "sent_to": "local (target host, default https://cloud.langfuse.com; printed to stderr if custom)" }, { "name": "LANGFUSE_MOCK_DATA", "sent_to": "local (test entry point only)" }, { "name": "NODE_ENV / DEBUG", "sent_to": "local (debug logging)" } ], "local": "Reads its own package.json. Writes the full text of any trace/observation field longer than 1000 characters to /tmp/langfuse___.txt (shared/truncation.js:13-39) and tells the AI the path; files are never deleted and use default permissions. On Windows '/tmp' resolves to \\tmp on the current drive.", "exec": "None.", "telemetry": "None.", "tools": [ "get_traces", "get_trace_detail", "get_observations", "get_observation" ], "toolText": "clean (descriptions disclose the /tmp truncation behaviour and suggest grep on those files)", "deps": [ "@modelcontextprotocol/sdk", "zod" ], "findings": [ { "severity": "note", "at": "shared/truncation.js:13-39", "what": "Large trace fields (often full LLM prompts and outputs, which can contain user data) are written in plain text to /tmp files that are never cleaned up and are readable by other local users on shared machines. Disclosed in the tool descriptions." }, { "severity": "info", "at": "shared/tools.js:6-11", "what": "All four tools are read-only GETs; no write or delete operations exist." }, { "severity": "info", "at": "build/index.integration-with-mock.js", "what": "A test entry point with a mock client is shipped in build/ (counted); it makes no network calls." }, { "severity": "info", "at": "shared/langfuse-client/lib/*.js", "what": "IDs are encodeURIComponent'd and filters go through URLSearchParams; no injection into the request path." }, { "severity": "info", "at": "package", "what": "No package.json in the reviewed copy (code reads it at runtime for the version); dependencies are taken from imports. No obfuscation, install hooks, dynamic code or hard-coded secrets." }, { "severity": "info", "at": "manifest.tsv", "what": "lines_read (1377) is the real line count of every file (Read tool / splitlines). The manifest's 1396 counts one extra empty 'line' after the trailing newline of 19 files; no file or line was skipped." } ] }, "health": { "score": 65, "parts": { "popularity": 0.4462981140576957, "activity": 0.6674452394758004, "issues": 0.7096774193548387, "security": 1 }, "fail": 0, "warn": 0, "raw": { "stars": 81, "forks": 10, "downloads": 235, "hn": { "n": 0, "pts": 0, "t": [] }, "issuesOpen": 27, "issuesClosed": 66, "prsMerged": 491, "commits90": 1, "release": "2025-07-03T16:10:39Z", "pushed": "2026-10-09T17:32:15Z", "growth": null, "growthDays": null, "archived": false }, "at": "2026-10-31T07:42:38.200Z" } }